Senseonics (SENS) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 05, 2021
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity File Number	001-37717
Entity Registrant Name	SENSEONICS HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-1210911
Entity Address, Address Line One	20451 Seneca Meadows Parkway
Entity Address, City or Town	Germantown
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20876-7005
City Area Code	301
Local Phone Number	515-7260
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SENS
Security Exchange Name	NYSEAMER
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		445,982,671
Entity Central Index Key	0001616543
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 46,211	$ 18,005
Restricted cash		200
Short term investments, net	96,566
Accounts receivable, net	124	565
Accounts receivable - related parties	3,549	2,421
Inventory, net	7,878	5,281
Prepaid expenses and other current assets	3,732	3,774
Total current assets	158,060	30,246
Option	236	1,886
Deposits and other assets	1,668	2,229
Long term investments, net	58,355
Property and equipment, net	1,305	1,557
Total assets	219,624	35,918
Current liabilities:
Accounts payable	793	1,762
Accrued expenses and other current liabilities	13,985	11,674
Term Loans, net	5,113	3,202
Total current liabilities	19,891	16,638
Long-term debt and notes payables, net	57,161	57,216
Derivative liabilities	317,304	62,119
Option	91,097	39,734
Other liabilities	817	1,483
Total liabilities	486,270	177,190
Preferred stock and additional paid-in-capital, subject to possible redemption: $0.001 par value per share; 0 shares issued and outstanding as of September 30, 2021 and 3,000 shares issued and outstanding as of December 31, 2020		2,811
Total temporary equity		2,811
Commitments and contingencies
Stockholders' deficit:
Common stock, $0.001 par value per share; 900,000,000 shares authorized; 445,615,196 and 265,582,688 shares issued and outstanding as of September 30, 2021 and December 31, 2020	446	266
Additional paid-in capital	768,324	504,162
Accumulated other comprehensive income, net of tax	2
Accumulated deficit	(1,035,418)	(648,511)
Total stockholders' deficit	(266,646)	(144,083)
Total liabilities and stockholders' deficit	$ 219,624	$ 35,918

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Class of stock information
Temporary equity, par or stated value per share	$ 0.001	$ 0.001
Temporary equity, shares issued	0	3,000
Temporary equity, shares outstanding	0	3,000
Common stock, par value per share (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	445,615,196	265,582,688
Common stock, shares outstanding	445,615,196	265,582,688

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss)
Revenue, net	$ 276	$ 514	$ 1,196	$ 761
Revenue, net - related parties	3,256	253	8,471	303
Total revenue	3,532	767	9,667	1,064
Cost of sales	4,778	(68)	9,995	21,006
Gross profit (loss)	(1,246)	835	(328)	(19,942)
Expenses:
Sales and marketing expenses	2,468	3,234	5,725	17,521
Research and development expenses	7,200	4,568	19,562	15,726
General and administrative expenses	5,117	5,501	17,622	15,635
Operating loss	(16,031)	(12,468)	(43,237)	(68,824)
Other income (expense), net:
Interest income	486	1	743	173
Gain (Loss) on fair value adjustment of option	13,556		(74,848)
Gain (Loss) on extinguishment of debt and option		(9,527)	330	(20,458)
Loss on issuance of debt & other issuance costs		(931)		(1,216)
Interest expense	(4,245)	(3,632)	(12,337)	(11,560)
Gain (Loss) on change in fair value of derivatives	50,075	3,520	(255,185)	29,069
Impairment cost	(488)		(1,650)
Other expense	(439)	(391)	(723)	(720)
Total other income (expense), net	58,945	(10,960)	(343,670)	(4,712)
Net Income (Loss)	42,914	(23,428)	(386,907)	(73,536)
Other comprehensive income, net of tax
Unrealized gain on marketable securities	18		2
Total other comprehensive income, net of tax	18		2
Total comprehensive income (loss), net of tax	$ 42,932	$ (23,428)	$ (386,905)	$ (73,536)
Basic net income (loss) per common share	$ 0.10	$ (0.10)	$ (0.93)	$ (0.33)
Basic weighted-average shares outstanding	445,378,308	236,519,812	414,128,283	220,250,060
Diluted net income (loss) per common share	$ 0.08	$ (0.10)	$ (0.93)	$ (0.33)
Diluted weighted-average shares outstanding	581,760,516	236,519,812	414,128,283	220,250,060

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-In Capital	AOCI Attributable to Parent [Member]	Accumulated Deficit	Series A Preferred Stock	Total
Balance at Dec. 31, 2019	$ 203	$ 464,491		$ (473,343)		$ (8,649)
Balance (in shares) at Dec. 31, 2019	203,453
Changes in Stockholders' Equity (Deficit)
Issuance of common stock, net		(86)				(86)
Issuance of common stock (in shares)	175
Exercise of stock options and ESPP purchases	$ 2	573				575
Exercise of stock options and ESPP purchases (in shares)	2,220
Exchange and conversion of convertible notes, net	$ 39	20,082				20,121
Exchange and conversion of convertible notes, net (in shares)	38,391
Stock-based compensation expense and vesting of RSUs		5,581				5,581
Issuance of warrants related to debt, net		1,212				1,212
Net income (loss)				(73,536)		(73,536)
Balance at Sep. 30, 2020	$ 244	491,853		(546,879)		(54,782)
Balance (in shares) at Sep. 30, 2020	244,239
Balance at Dec. 31, 2019	$ 203	464,491		(473,343)		(8,649)
Balance (in shares) at Dec. 31, 2019	203,453
Changes in Stockholders' Equity (Deficit)
Net income (loss)						(175,200)
Balance at Dec. 31, 2020	$ 266	504,162		(648,511)		(144,083)
Balance (in shares) at Dec. 31, 2020	265,582
Temporary Equity, Ending Balance at Dec. 31, 2020					$ 2,811
Balance at Jun. 30, 2020	$ 231	483,615		(523,451)		(39,605)
Balance (in shares) at Jun. 30, 2020	230,553
Changes in Stockholders' Equity (Deficit)
Exercise of stock options and ESPP purchases	$ 1	76				77
Exercise of stock options and ESPP purchases (in shares)	1,188
Exchange and conversion of convertible notes, net	$ 12	5,859				5,871
Exchange and conversion of convertible notes, net (in shares)	12,498
Stock-based compensation expense and vesting of RSUs		2,303				2,303
Net income (loss)				(23,428)		(23,428)
Balance at Sep. 30, 2020	$ 244	491,853		(546,879)		(54,782)
Balance (in shares) at Sep. 30, 2020	244,239
Balance at Dec. 31, 2020	$ 266	504,162		(648,511)		(144,083)
Balance (in shares) at Dec. 31, 2020	265,582
Changes in Stockholders' Equity (Deficit)
Conversion of preferred stock	$ 54	45,512				45,566
Conversion of preferred stock (in shares)	54,166
Issuance of common stock, net	$ 113	200,327				200,440
Issuance of common stock (in shares)	112,571
Exercise of stock options and warrants	$ 5	4,622				4,627
Exercise of stock options and warrants (in shares)	5,501
Exchange and conversion of convertible notes, net	$ 5	6,496				6,501
Exchange and conversion of convertible notes, net (in shares)	4,925
Issued common stock for vested RSUs and ESPP purchase	$ 3	71				74
Issued common stock for vested RSUs and ESPP purchase (in shares)	2,870
Stock-based compensation expense		7,134				7,134
Net income (loss)				(386,907)		(386,907)
Other comprehensive income, net of tax			$ 2			2
Balance at Sep. 30, 2021	$ 446	768,324	2	(1,035,418)		(266,646)
Balance (in shares) at Sep. 30, 2021	445,615
Increase (Decrease) in Temporary Equity
Issuance of convertible preferred stock, net					42,756
Conversion of preferred stock					$ (45,567)
Balance at Jun. 30, 2021	$ 445	765,262	(16)	(1,078,332)		(312,641)
Balance (in shares) at Jun. 30, 2021	445,125
Changes in Stockholders' Equity (Deficit)
Exercise of stock options and warrants	$ 1	737				738
Exercise of stock options and warrants (in shares)	474
Issued common stock for vested RSUs and ESPP purchase		24				24
Issued common stock for vested RSUs and ESPP purchase (in shares)	16
Stock-based compensation expense		2,301				2,301
Net income (loss)				42,914		42,914
Other comprehensive income, net of tax			18			18
Balance at Sep. 30, 2021	$ 446	$ 768,324	$ 2	$ (1,035,418)		$ (266,646)
Balance (in shares) at Sep. 30, 2021	445,615

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (386,907)	$ (73,536)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	918	853
Non-cash interest expense (debt discount and deferred costs)	5,825	7,200
Change in fair value of derivatives	255,185	(29,069)
Loss on fair value adjustment of option	74,848
(Gain) Loss on extinguishment of debt and option	(330)	20,458
Impairment cost	1,650
Stock-based compensation expense	7,134	5,581
Loss on disposal of assets		181
Changes in assets and liabilities:
Accounts receivable	(686)	9,880
Prepaid expenses and other current assets	41	(77)
Inventory	(2,597)	12,645
Deposits and other assets	(30)	117
Accounts payable	(971)	(3,336)
Accrued expenses and other liabilities	1,319	(8,608)
Accrued interest	326	(877)
Operating lease liabilities		(586)
Net cash used in operating activities	(44,275)	(59,174)
Cash flows from investing activities
Capital expenditures	(75)	(181)
Purchase of marketable securities	(154,918)
Net cash used in investing activities	(154,993)	(181)
Cash flows from financing activities
Issuance of common stock, net	200,440	(87)
Proceeds from exercise of stock options, stock warrants and ESPP purchases	4,701	576
Proceeds from debt issuance, net		55,971
Proceeds from issuance of Masters preferred stock, net	22,783
Repayment of term loans	(650)	(66,050)
Cost of issuance of Second Lien Notes		(601)
Net cash provided by (used in) financing activities	227,274	(10,191)
Net increase (decrease) in cash, cash equivalents and restricted cash	28,006	(69,546)
Cash, cash equivalents and restricted cash, at beginning of period	18,205	95,938
Cash, cash equivalents and restricted cash, at ending of period	46,211	26,392
Supplemental disclosure of cash flow information
Cash paid during the period for interest	$ 6,149	5,600
Supplemental disclosure of non-cash investing and financing activities
Issuance of common stock converted from notes payables		300
Exchange of 2025 Notes for Second Lien Notes		(24,000)
Issuance of Second Lien Notes		$ 15,675

Organization and Nature of Oper

Organization and Nature of Operations	9 Months Ended
	Sep. 30, 2021
Organization and Nature of Operations
Organization and Nature of Operations	​ 1. Organization and Nature of Operations ​ Senseonics Holdings, Inc., a Delaware corporation, is a medical technology company focused on the development and commercialization of long-term, implantable continuous glucose monitoring (“CGM”) systems to improve the lives of people with diabetes by enhancing their ability to manage their disease with relative ease and accuracy. Senseonics, Incorporated is a wholly owned subsidiary of Senseonics Holdings and was originally incorporated on October 30, 1996 and commenced operations on January 15, 1997. Senseonics Holdings and Senseonics, Incorporated are hereinafter collectively referred to as the “Company” unless otherwise indicated or the context otherwise requires.

Liquidity and Capital Resources

Liquidity and Capital Resources	9 Months Ended
	Sep. 30, 2021
Liquidity and Capital Resources
Liquidity and Capital Resources	2. Liquidity and Capital Resources ​ From its founding in 1996 until 2010, the Company has devoted substantially all of its resources to researching various sensor technologies and platforms. Beginning in 2010, the Company narrowed its focus to developing and refining a commercially viable glucose monitoring system. However, to date, the Company has not generated any significant revenue from product sales. The Company has incurred substantial losses and cumulative negative cash flows from operations since its inception in October 1996. The Company has never been profitable from operations, and its net losses were $175.2 million, $115.5 million, and $94.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. As of September 30, 2021, the Company had an accumulated deficit of $1.0 billion. To date, the Company has funded its operations principally through the issuance of preferred stock, common stock, convertible note issuance and debt. As of September 30, 2021, the Company had cash, cash equivalents and marketable securities of $201.1 million. ​ In November 2019, the Company entered into an Open Market Sale Agreement with Jefferies LLC, under which the Company could offer and sell, from time to time at its sole discretion, shares of its common stock having an aggregate offering price of up to $50.0 million through Jeffries as its sales agent in an “at the market” offering. In June 2021, the Company received $48.4 million in net proceeds from the sale of 12,830,333 shares of its common stock utilizing the full capacity under the 2019 Sales Agreement. For the nine months ended September 30, 2020, the Company had received $0.1 million in net proceeds from the sale of 175,289 shares of its common stock under the 2019 Sales Agreement. ​ On January 21, 2021, the Company entered into an underwriting agreement, which was subsequently amended and restated on the same day (the “Underwriting Agreement”) with H.C. Wainwright & Co., LLC, as representative of the underwriters (the “Underwriters”), to issue and sell 51,948,052 shares of common stock, in an underwritten public offering pursuant to effective registration statements on Form S-3, including a related prospectus and prospectus supplement, in each case filed with the Securities and Exchange Commission (the “Offering”). The price to the public in the Offering was $1.925 per share of common stock. The Underwriters agreed to purchase the shares from the Company pursuant to the Underwriting Agreement at a price of $1.799875 per share and the Company also agreed to reimburse them for customary fees and expenses. The initial closing of the Offering occurred on January 26, 2021. Subsequent to the initial closing, the Underwriters exercised their option to purchase an additional 7,792,207 shares of common stock. Total net proceeds from the Offering were $106.1 million after deducting underwriting discounts and commissions and estimated offering expenses. ​ On January 17, 2021, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with certain institutional purchasers (the “Purchasers”), pursuant to which the Company sold to the Purchasers, in a registered direct offering (the “Registered Direct Offering”), an aggregate of 40,000,000 shares (the “Shares”) of common stock, $0.001 par value per share. The Shares were sold at a purchase price of $1.25 per share for aggregate gross proceeds to the Company of $50.0 million, before deducting fees to the placement agent and other estimated offering expenses payable by the Company. The Shares were offered and sold by the Company pursuant to an effective shelf registration statement on Form S-3, which was originally filed with the Securities and Exchange Commission on November 27, 2019. The net proceeds to the Company from the Registered Direct Offering, after deducting fees and expenses and the estimated offering expenses payable by the Company, are approximately $46.1 million. ​ On November 9, 2020, the Company entered into an equity line agreement (the “Equity Line Agreement”) with Energy Capital, LLC, a Florida limited liability company (“Energy Capital”), which provides that, upon the terms and subject to the conditions and limitations set forth therein, Energy Capital is committed to purchase up to an aggregate of $12.0 million of shares of the Company’s newly designated series B convertible preferred stock (the “Series B Preferred Stock”) at the Company’s request from time to time during the 24-month term of the Equity Line Agreement. Under the Equity Line Agreement, beginning January 21, 2021, subject to the satisfaction of certain conditions, including the Company has less than $8 million of cash, cash equivalents and other available credit (aside from availability under the Equity Line Agreement), the Company has the right, at its sole discretion, to present Energy Capital with a purchase notice (each, a “Regular Purchase Notice”) directing Energy Capital (as principal) to purchase shares of Series B Preferred Stock at a price of $1,000 per share (not to exceed $4.0 million worth of shares) once per month, up to an aggregate of $12.0 million of our Series B Preferred Stock at a per share price (the “Purchase Price”) equal to $1,000 per share of Series B Preferred Stock, with each share of Series B Preferred Stock initially convertible into common stock, beginning six months after the date of its issuance, at a conversion price of $0.3951 per share, subject to customary anti-dilution adjustments, including in the event of any stock split. The Equity Line Agreement provides that the Company shall not affect any Regular Purchase under the Equity Line Agreement on any date where the closing price of the Company’s common stock on the NYSE American is less than $0.25 without the approval of Energy Capital. In addition, beginning on January 1, 2022, subject to the satisfaction of certain conditions, if the full $12.0 million of Series B Preferred Stock has not been sold pursuant to Regular Purchases, Energy Capital may, at its sole discretion, by its delivery to the Company of a Purchase Notice, from time to time, purchase up to the amount then remaining available under the Equity Line Agreement at the Purchase Price. ​ On August 9, 2020, the Company entered into a financing agreement with the parent company of Ascensia Diabetes Care Holdings AG (“Ascensia”), PHC Holdings Corporation (“PHC”), pursuant to which the Company issued $35.0 million in aggregate principal amount of Senior Secured Convertible Notes due on October 31, 2024 (the “PHC Notes”), to PHC. The Company also issued 2,941,176 shares of common stock to PHC as a financing fee. The Company also has the option to sell and issue PHC up to $15.0 million of convertible preferred stock on or before December 31, 2022, contingent upon obtaining approval for the 180-day Eversense product for marketing in the United States before such date. ​ Additionally, on August 9, 2020, the Company entered into a Stock Purchase Agreement with Masters Special Solutions, LLC and certain affiliates thereof (“Masters”), pursuant to which the Company issued and sold to Masters 3,000 shares of convertible preferred stock, designated as “Series A Preferred Stock” (the “Series A Preferred Stock”), at a price of $1,000.00 per share in an initial closing. Masters also had the option to purchase up to an additional 27,000 shares of Series A Preferred Stock at a price of $1,000.00 per share in subsequent closings, subject to the terms and conditions of the Stock Purchase Agreement, as amended, through January 11, 2021. In January 2021, Masters and its assignees purchased in aggregate an additional 22,783 shares of Series A Preferred Stock, resulting in additional gross proceeds to the Company of $22.8 million. Each share of Series A Preferred Stock was initially convertible into a number of shares of common stock equal to $1,000.00 divided by the conversion price of $0.476 per share, subject to customary anti-dilution adjustments, including in the event of any stock split. All shares of Series A Preferred Stock have been converted to common stock as of September 30, 2021.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	​ 3. Summary of Significant Accounting Policies ​ Basis of Presentation ​ The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Although the Company considers the disclosures in these unaudited consolidated financial statements to be adequate to make the information presented not misleading, certain information or footnote information normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted as permitted under the rules and regulations of the United States Securities and Exchange Commission (“SEC”). In the opinion of management, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair statement of financial position at September 30, 2021, and December 31, 2020, results of operations, comprehensive income (loss), and changes in stockholder’s equity (deficit) for the three and nine months ended September 30, 2021, and 2020 and cash flows for the nine months ended September 30, 2021, and 2020 have been included. The unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the SEC on March 5, 2021. The interim results for September 30, 2021, are not necessarily indicative of the results to be expected for the year ending December 31, 2021, or for any future interim periods. The consolidated financial statements reflect the accounts of Senseonics Holdings, Inc. and its wholly owned operating subsidiary Senseonics Incorporated. Use of Estimates ​ The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenue and expenses during the reporting period. In the accompanying unaudited consolidated financial statements, estimates are used for, but not limited to, stock-based compensation, recoverability of long-lived assets, deferred taxes and valuation allowances, derivative assets and liabilities, obsolete inventory, warranty obligations, variable consideration related to revenue, depreciable lives of property and equipment, and accruals for clinical study costs, which are accrued based on estimates of work performed under contract. The Company considered COVID-19 related impacts to its estimates, as appropriate, within its unaudited condensed consolidated financial statements and there may be changes to those estimates in future periods due to the uncertainties surrounding the severity and duration of the COVID-19 pandemic. Actual results could differ from those estimates; however, management does not believe that such differences would be material. ​ Segment Information ​ The Company views its operations and manages its business in one segment, glucose monitoring products. ​ Comprehensive Loss ​ Comprehensive income (loss) comprises net income (loss) and other changes in equity that are excluded from net income (loss). For the three and nine months ended September 30, 2021, the Company’s comprehensive income (loss) included less than $0.1 million of other comprehensive income related to the unrealized gain on marketable securities. For the three and nine months ended September 30, 2020, the Company’s net loss equaled its comprehensive loss and, accordingly, no additional disclosure is presented. ​ Cash and Cash Equivalents ​ The Company considers highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. These investments are carried at cost, which approximates fair value. Cash and cash equivalents consisted of the following as of the periods listed below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash ⁽ ¹ ⁾ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,393 ​ $ 18,002 ​ Money market funds ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 43,818 ​ ​ 3 ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 ​ (1) Includes overnight repurchase agreements ​ Restricted Cash ​ The Company’s restricted cash previously included pledged cash as collateral related to its credit card program with Silicon Valley Bank (“SVB”). The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statement of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 Restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ 200 Cash, cash equivalents and restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,205 ​ Long-lived Assets Management reviews long-lived assets, including property and equipment and right-of-use assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of the long-lived asset is measured by a comparison of the carrying amount of the asset to future undiscounted net cash flows expected to be generated by the asset. If the undiscounted cash flows are less than the carrying amount, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets. Management identified an indicator of impairment for a right of use asset and recorded an immaterial expense for the nine months ended September 30, 2021. There was no impairment recorded for the three months ended September 30, 2021. Warranty Obligation The Company provides a warranty of one year on its smart transmitters. Additionally, the Company may also replace Eversense system components that do not function in accordance with the product specifications. Estimated replacement costs are recorded at the time of shipment as a charge to cost of sales in the consolidated statement of operations and are developed by analyzing product performance data and historical replacement experience, including comparing actual replacements to revenue. At September 30, 2021, and December 31, 2020, the warranty reserve for both periods was $0.6 million. The following table provides a reconciliation of the change in estimated warranty liabilities for the nine months ended September 30, 2021 and for the twelve months ended December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2021 2020 Balance at beginning of the period ​ $ 646 ​ $ 2,197 Provision for warranties during the period ​ ​ 760 ​ ​ (266) Settlements made during the period ​ ​ (844) ​ ​ (1,285) Balance at end of the period ​ $ 562 ​ $ 646 ​ Revenue The Company recognizes revenue in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company generates revenue from sales of its Eversense CGM system and related components at a fixed price to third-party distributors in the European Union and to strategic fulfillment partners in the United States, and a combination of fixed and variable prices to its strategic partner, Ascensia (collectively, “Customers”), who then resell the products to health care providers and patients. The Company is paid for its sales directly to the Customers, regardless of whether or not the Customers resell the products to health care providers and patients. Customer contracts do not include the right to return unless there is a product issue, in which case the Company may provide replacement product. Product conformity guarantees do not create additional performance obligations and are accounted for as warranty obligations in accordance with guarantee and loss contingency accounting guidance. Revenue is recognized, at a point in time, when the Customers obtain control of the product based upon the delivery terms as defined in the contract, at an amount that reflects the consideration which is expected to be received in exchange for the product. Contracts with the Customers include performance obligations for supply of goods and the performance obligation is typically satisfied upon transfer of control of the product. Distribution contracts may also contain requirements for training and customer service support; however, these are not assessed as performance obligations given the activities are considered immaterial in the context of the contract. The payment terms and conditions of the Customers vary, but the Company is typically paid within 60 days of invoicing subsequent to the Customers obtaining control of the Company’s product. The Company’s contracts contain variable consideration such as prompt-pay discounts, tier-volume price discounts and for the Ascensia commercial agreement, revenue share. Variable consideration, such as discounts and prompt-pay incentives, are treated as a reduction in revenue and variable consideration, such as revenue share is treated as an addition in revenue when the product sale is recognized. The amount of variable consideration that is included in the transaction price may be constrained and is included in revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period, when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgement. Depending on the variable consideration, the Company estimates the expected value based on the terms of the agreements, historical data, geographic mix, reimbursement rates, and market conditions. The Company’s estimates used in determining the variable consideration on a sale transaction may be adjusted each reporting period depending on actual results, provided a change does not reflect a modification to the original contract. Contract assets consist of trade receivables and unbilled receivables from customers and are recorded at net realizable value. Unbilled receivables relate to the revenue share variable consideration from the Ascensia commercial agreement. ​ Concentration of Revenue and Customers ​ For the three months ended September 30, 2021, the Company derived 92% of its total revenue from one customer, Ascensia. For the three months ended September 30, 2020, the Company derived 33% of its total revenue from one customer, Roche Diabetes Care GmbH. For the nine months ended September 30, 2021, the Company derived 88% of its total revenue from one customer, Ascensia. For the nine months ended September 30, 2020, the Company derived 29% of its total revenue from one customer, Roche Diabetes Care GmbH. Revenues for these corresponding periods represent purchases for sensors, transmitters and miscellaneous Eversense system components. ​ Revenue by Geographic Region ​ The following table sets forth net revenue derived from the Company’s two primary geographical markets, the United States and outside of the United States, based on the geographic location to which the Company delivers the product, for the three and nine months ended September 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2021 ​ ​ September 30, 2021 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 2,928 ​ 82.9 % ​ $ 7,771 ​ 80.4 % United States ​ 604 ​ 17.1 ​ ​ ​ 1,896 ​ 19.6 ​ Total $ 3,532 ​ 100.0 % ​ $ 9,667 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2020 ​ ​ September 30, 2020 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 258 ​ 33.6 % ​ $ 325 ​ 30.5 % United States ​ 509 ​ 66.4 ​ ​ ​ 739 ​ 69.5 ​ Total $ 767 ​ 100.0 % ​ $ 1,064 ​ 100.0 % ​ ​ Marketable Securities Marketable securities consist of commercial paper, corporate debt securities, asset backed securities and government and agency securities. The Company’s investments are classified as available for sale. Such securities are carried at fair value, with any unrealized holding gains or losses reported, net of any tax effects reported, as accumulated other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, are included in consolidated results of operations. A decline in the market value of any available for sale security below cost that is deemed to be other-than-temporary results in a reduction in fair value, which is charged to earnings in that period, and a new cost basis for the security is established. Dividend and interest income is recognized when earned. The cost of securities sold is calculated using the specific identification method. The Company classifies all available-for-sale marketable securities with maturities greater than one year from the balance sheet date as non-current assets. ​ Accounts Receivable ​ Accounts receivable consist of amounts due from the Company’s Customers and are recorded at net realizable value, which may include reductions for allowances for doubtful accounts at the time potential collection risk is identified or for promotional or prompt-pay discounts offered. The Company does not have a history of collectability concerns and no allowance for uncollectible accounts was recorded as of September 30, 2021, however, an immaterial allowance for uncollectible accounts was recorded as of December 31, 2020. Accounts receivable as of September 30, 2021 included unbilled accounts receivable of $2.0 million. The Company expects to invoice and collect all unbilled accounts receivable within 12 months. ​ ​ ​ ​ Net Income (Loss) per Share ​ Basic net income per share attributable to common stockholders is calculated by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares outstanding during the period and, when dilutive, potential common share equivalents. Basic net loss per share is computed by dividing net loss available to common stockholders by the weighted average number of shares of common stock outstanding during the period. ​ Potentially dilutive common shares consist of shares issuable from restricted stock units, warrants, and our convertible notes. Potentially dilutive common shares issuable upon vesting of restricted stock units and exercise of stock options and warrants are determined using the average share price for each period under the treasury stock method. Potentially dilutive common shares issuable upon conversion of our convertible notes are determined using the if converted method. In periods of net loss, all potentially dilutive common shares are excluded from the computation of the diluted net loss per share for those periods, as the effect would be anti-dilutive. ​ The following table sets forth the computation of basic and diluted net income per share for the periods shown: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2021 2020 ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) ​ 42,914 ​ (23,428) ​ (386,907) ​ (73,536) Impact of conversion of dilutive securities ​ 1,385 ​ - ​ - ​ - ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive Net income (loss) ​ 44,299 ​ (23,428) ​ (386,907) ​ (73,536) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) per share ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ 0.10 ​ (0.10) ​ (0.93) ​ (0.33) Diluted ​ 0.08 ​ (0.10) ​ (0.93) ​ (0.33) ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted average shares outstanding ​ 445,378,308 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060 Dilutive potential common stock outstanding ​ ​ ​ ​ ​ ​ ​ ​ Stock-based awards ​ 15,520,414 ​ - ​ - ​ - 2023 Notes ​ 4,617,646 ​ - ​ - ​ - 2025 Notes ​ 39,689,142 ​ - ​ - ​ - PHC Notes ​ 65,348,857 ​ - ​ - ​ - Warrants ​ 11,206,148 ​ - ​ - ​ - Diluted weighted average shares outstanding ​ 581,760,516 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060 ​ For the nine months ended September 30, 2021, as well as for the three and nine months ended September 30, 2020, the Company operated at a loss. Accordingly, all potentially dilutive shares were considered antidilutive, and basic and diluted EPS are the same. ​ Outstanding anti-dilutive securities not included in the diluted net income per share attributable to common stockholders calculations were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2021 2020 ​ 2021 ​ 2020 Stock-based awards ​ 1,949,958 ​ 27,972,959 ​ 28,502,846 ​ 27,972,959 2023 Notes ​ — ​ 6,672,500 ​ 4,617,646 ​ 6,672,500 2025 Notes ​ — ​ 44,429,624 ​ 39,689,142 ​ 44,429,624 PHC Notes ​ — ​ 65,359,000 ​ 65,757,177 ​ 65,359,000 Second Lien Notes ​ — ​ 18,085,140 ​ — ​ 18,085,140 Warrants ​ 116,581 ​ 9,696,581 ​ 13,177,822 ​ 9,696,581 Total anti-dilutive shares outstanding ​ 2,066,539 ​ 172,215,804 ​ 151,744,633 ​ 172,215,804 ​ Exit or Disposal Costs ​ Costs associated with exit or disposal activities, such as restructuring, sale or termination of a line of business, the closure of business activities in a particular location, the relocation of business activities, changes in management structure and a fundamental reorganization that affects the nature and focus of operations, are recognized and measured initially at their fair values during the period in which an obligation meets the definition of a liability. There were no exit or disposal activities for the three and nine months ended September 30, 2021. The Company’s workforce reduction on March 26, 2020 did not permit continuation of service past March 31, 2020 and associated one-time employee termination benefit costs in the amount of $1.4 million were paid and recorded in the Company’s accompanying unaudited consolidated financial statements for the nine months ended September 30, 2020. ​ ​ Recent Accounting Pronouncements ​ Recently Adopted ​ In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes ​ Not Yet Adopted ​ In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments ​ In August 2020, the FASB issued ASU 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contract in Entity’s Own Equity (Subtopic 815-40).

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2021
Marketable Securities
Marketable Securities	4. Marketable Securities ​ Marketable securities available for sale, were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ ​ ​ Gross ​ Gross ​ Estimated ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Market ​ Cost Gains Losses Value Commercial Paper ​ $ 62,336 ​ ​ — ​ ​ — ​ $ 62,336 Corporate debt securities ​ $ 40,084 ​ ​ 5 ​ ​ (4) ​ $ 40,085 Asset backed securities ​ $ 27,869 ​ ​ 5 ​ ​ (4) ​ $ 27,870 Government and agency securities ​ $ 24,630 ​ ​ 5 ​ ​ (5) ​ $ 24,630 Total ​ $ 154,919 ​ $ 15 ​ $ (13) ​ $ 154,921 ​ The following are the scheduled maturities as of September 30, 2021 (in thousands): ​ ​ ​ ​ ​ 2021 (remaining three months) $ 4,999 2022 ​ ​ 149,922 2023 ​ — 2024 ​ ​ — Thereafter ​ ​ — Total $ 154,921 ​

Inventory, net

Inventory, net	9 Months Ended
	Sep. 30, 2021
Inventory, net
Inventory, net	5. Inventory, net ​ Inventory, net of reserves, consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 2020 Finished goods $ 1,927 $ 203 Work-in-process ​ 4,513 ​ 2,626 Raw materials ​ 1,438 ​ 2,452 Total ​ $ 7,878 ​ $ 5,281 ​ The Company charged $1.8 million to cost of sales for the nine months ended September 30, 2021 and $15.1 million to cost of sales for the nine months ended September 30, 2020, to reduce the value of inventory for items that are potentially obsolete due to expiry, in excess of product demand, or to adjust costs to their net realizable value .

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2021
Prepaid Expenses and Other Current Assets
Prepaid Expenses and Other Current Assets	6. Prepaid Expenses and Other Current Assets ​ Prepaid expenses and other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 Contract manufacturing⁽¹⁾ ​ $ 2,431 ​ $ 3,324 Interest receivable ​ 378 ​ — Insurance ​ ​ 266 ​ ​ 50 IT and software ​ 266 ​ 150 Research and development ​ ​ 115 ​ ​ — Rent ​ ​ 105 ​ ​ 102 Other ​ 171 ​ 148 Total prepaid expenses and other current assets ​ $ 3,732 ​ $ 3,774 ​ (1) Includes deposits to contract manufacturers for manufacturing process .

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2021
Accrued Expenses and Other Current Liabilities
Accrued Expenses and Other Current Liabilities	7. Accrued Expenses and Other Current Liabilities ​ Accrued expenses and other current liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 Compensation and benefits ​ $ 3,010 ​ $ 4,344 Interest on notes payable ​ 2,098 ​ 1,773 Professional and administration services ​ ​ 1,945 ​ ​ 880 Product warranty and replacement obligations ​ ​ 1,783 ​ ​ 646 Contract manufacturing ​ ​ 1,629 ​ ​ 1,421 Research and development ​ 1,454 ​ 842 Sales and marketing services ​ 1,149 ​ 615 Operating lease ​ ​ 875 ​ ​ 794 Other ​ ​ 42 ​ ​ 151 Patient access programs ​ ​ — ​ ​ 208 Total accrued expenses and other current liabilities ​ $ 13,985 ​ $ 11,674 ​

Notes Payable, Preferred Stock

Notes Payable, Preferred Stock and Stock Purchase Warrants	9 Months Ended
	Sep. 30, 2021
Notes Payable, Preferred Stock and Stock Purchase Warrants
Notes Payable, Preferred Stock and Stock Purchase Warrants	8. Notes Payable, Preferred Stock and Stock Purchase Warrants ​ Term Loans ​ PPP Loan ​ On April 22, 2020, the Company received $5.8 million in loan funding from the PPP pursuant to the CARES Act, as amended by the Flexibility Act, and administered by the Small Business Administration (“SBA”). The unsecured loan (the “PPP Loan”) is evidenced by the PPP Note dated April 21, 2020 (the “PPP Note”) in the principal amount of $5.8 million with SVB. ​ Under the terms of the PPP Note and the PPP Loan, interest accrues on the outstanding principal at a rate of 1.0% per annum. The term of the PPP Note is two years , though it may be payable sooner in connection with an event of default under the PPP Note. The Company began to make equal monthly payments of principal and interest, beginning in the third quarter of 2021. ​ The PPP Note may be prepaid in part or in full, at any time, without penalty. The PPP Note provides for certain customary events of default, including (i) failing to make a payment when due under the PPP Note, (ii) failure to do anything required by the PPP Note or any other loan document, (iii) defaults of any other loan with SVB, (iv) failure to disclose any material fact or make a materially false or misleading representation to SVB or SBA, (v) default on any loan or agreement with another creditor, if SVB believes the default may materially affect the Company’s ability to pay the PPP Note, (vi) failure to pay any taxes when due, (vii) becoming the subject of a proceeding under any bankruptcy or insolvency law, having a receiver or liquidator appointed for any part of the Company’s business or property, or making an assignment for the benefit of creditors, (viii) having any adverse change in financial condition or business operation that the SVB believes may materially affect the Company’s ability to pay the PPP Note, (ix) if the Company reorganizes, merges, consolidates, or otherwise changes ownership or business structure without the SVB’s prior written consent, or (x) becoming the subject of a civil or criminal action that SVB believes may materially affect the Company’s ability to pay the PPP Note. Upon the occurrence of an event of default, SVB has customary remedies and may, among other things, require immediate payment of all amounts owed under the PPP Note, collect all amounts owing from the Company, and file suit and obtain judgment against the Company. ​ ​ Convertible Preferred Stock and Warrants ​ On November 9, 2020, the Company entered into the (the “Equity Line Agreement”) with Energy Capital, LLC, which provides that, upon the terms and subject to the conditions and limitations set forth therein, Energy Capital is committed to purchase up to an aggregate of $12.0 million of shares of the Company’s newly designated series B convertible preferred stock (the “Series B Preferred Stock”) at the Company’s request from time to time during the 24-month term of the Equity Line Agreement. Under the Equity Line Agreement, beginning January 21, 2021, subject to the satisfaction of certain conditions, including the Company having less than $8 million of cash, cash equivalents and other available credit (aside from availability under the Equity Line Agreement), the Company has the right, at sole discretion, to present Energy Capital with a purchase notice (each, a “Regular Purchase Notice”) directing Energy Capital (as principal) to purchase shares of Series B Preferred Stock at a price of $1,000.00 per share (not to exceed $4.0 million worth of shares) once per month, up to an aggregate of $12.0 million of our Series B Preferred Stock at a per share price (the “Purchase Price”) equal to $1,000.00 per share of Series B Preferred Stock, with each share of Series B Preferred Stock initially convertible into common stock, beginning six months after the date of its issuance, at a conversion price of $0.3951 per share, subject to customary anti-dilution adjustments, including in the event of any stock split. The Equity Line Agreement provides that the Company shall not affect any Regular Purchase under the Equity Line Agreement on any date where the closing price of our common stock on the NYSE American is less than $0.25 without the approval of Energy Capital. In addition, beginning on January 1, 2022, subject to the satisfaction of certain conditions, if the full $12.0 million of Series B Preferred Stock has not been sold pursuant to Regular Purchases, Energy Capital may, at its sole discretion, by its delivery to the Company of a Purchase Notice, from time to time, purchase up to the amount then remaining available under the Equity Line Agreement at the Purchase Price. ​ The Company accounted for the Equity Line Agreement as a put/call option (the “Energy Capital Option”). This put/call option is classified as a liability in accordance with ASC 480 on the Company’s balance sheet and was recorded at the estimated fair value of $4.2 million upon issuance. The put/call option is required to be remeasured to fair value at each reporting period with the change recorded in change in fair value of derivatives that is a component of other income (expense). In connection with the issuance of the Equity Line Agreement, the Company incurred $7.6 million in debt issuance costs. The fair value as of September 30, 2021 was $91.1 million. ​ Concurrently with entry into the Equity Line Agreement, the Company issued a warrant to Energy Capital, exercisable beginning May 9, 2021, to purchase up to 10,000,000 shares of common stock at an exercise price of $0.3951 per share (the “Warrant”). The Warrant expires, if unexercised, on November 9, 2030. ​ On August 9, 2020, the Company entered into a Stock Purchase Agreement with Masters, pursuant to which the Company issued and sold to Masters 3,000 shares of Series A Preferred Stock, at a price of $1,000.00 per share in an initial closing. Masters also had the option to purchase up to an additional 27,000 shares of Series A Preferred Stock at a price of $1,000.00 per share in subsequent closings, subject to the terms and conditions of the Stock Purchase Agreement, as amended, through January 11, 2021. In January 2021, Masters and its assignees purchased in aggregate an additional 22,783 shares of Series A Preferred Stock, resulting in additional gross proceeds of $22.8 million. Each share of Series A Preferred Stock was initially convertible into a number of shares of common stock equal to $1,000.00 divided by the conversion price of $0.476 per share, subject to customary anti-dilution adjustments, including in the event of any stock split. As of September 30, 2021, all 25,783 shares of Series A Preferred Stock have been converted to common stock. Masters’ option to purchase the remaining unissued shares of Series A Preferred Stock expired on January 11, 2021, resulting in a gain on extinguishment of $3.5 million. ​ Convertible Notes ​ Highbridge Loan Agreement ​ On April 21, 2020, the Company entered into the Highbridge Loan Agreement with certain funds managed by Highbridge Capital Management, LLC (“Highbridge”), as the lenders (together with the other lenders from time to time party thereto, the “Lenders”) and Wilmington Savings Fund Society, SCB, as collateral agent. Pursuant to the Highbridge Loan Agreement, the Company borrowed an aggregate principal amount of $15.0 million in aggregate principal through the issuance and sale of First Lien Notes (the “First Lien Notes”) on April 24, 2020. In connection with the Highbridge Loan Agreement and receipt of the first tranche of borrowing, the Company issued 1,500,000 shares of its common stock to the Lenders as a commitment fee. On August 14, 2020, the Company prepaid the First Lien Notes in full, including the discounted prepayment premium, in the amount of approximately $17.6 million and recognized a loss on extinguishment in the amount of $0.7 million. ​ Exchange Agreement with Highbridge ​ On April 21, 2020, the Company entered into a Note Purchase and Exchange Agreement with certain funds managed by Highbridge providing for the exchange of $24.0 million aggregate principal amount of the Company’s outstanding 2025 Notes for (i) $15.7 million aggregate principal amount of newly issued Second Lien Notes , (ii) 11,026,086 shares of common stock, (iii) warrants to purchase up to 4,500,000 shares of common stock at an exercise price of $0.66 per share, and (iv) $0.3 million in accrued and unpaid interest on the 2025 Notes being exchanged (the “Exchange”). The Exchange closed on April 24, 2020. During 2020, Highbridge voluntarily converted all $15.7 million of outstanding principal amount of the Second Lien Notes for 42,776,936 shares of the Company’s common stock. ​ ​ PHC Notes ​ On August 9, 2020, the Company entered into a Note Purchase Agreement (the “Note Purchase Agreement”) with PHC, as the purchaser (together with the other purchasers from time to time party thereto, the “Note Purchasers”) and Alter Domus (US) LLC, as collateral agent. Pursuant to the Note Purchase Agreement, the Company borrowed $35.0 million in aggregate principal through the issuance and sale of the PHC Notes on August 14, 2020 (the “Closing Date”). The Company also issued 2,941,176 shares of its common stock, $0.001 par value per share to PHC as a financing fee (the “Financing Fee Shares”) on the Closing Date. The Financing Fee Shares are accounted for as debt discount in the amount of $1.5 million. ​ The PHC Notes are senior secured obligations of the Company and will be guaranteed on a senior secured basis by the Company’s wholly owned subsidiary, Senseonics, Incorporated. Interest at the annual rate of 9.5% will be payable semi-annually in cash or, at the Company’s option, payment in kind. The interest rate will decrease to 8.0% if the Company obtains approval for 180-day Eversense for marketing in the United States, subject to certain conditions. The maturity date for the PHC Notes is October 31, 2024 (the “Maturity Date”). The obligations under the PHC Notes are secured by substantially all of the Company’s and its subsidiary’s assets. ​ The Note Purchasers are entitled to convert the PHC Notes to common stock at a conversion rate of 1,867.4136 shares per $1,000 principal amount of the PHC Notes (including any interest added thereto as payment in kind), equivalent to a conversion price of approximately $0.54 per share, subject to specified anti-dilution adjustments, including adjustments for the Company’s issuance of equity securities on or prior to April 30, 2022 below the conversion price. In addition, following a notice of redemption or certain corporate events that occur prior to the maturity date, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its PHC Notes in connection with such notice of redemption or corporate event. In certain circumstances, the Company will be required to pay cash in lieu of delivering make whole shares unless the Company obtains stockholder approval to issue such shares. ​ Subject to specified conditions, on or after October 31, 2022, the PHC Notes are redeemable by the Company if the closing sale price of the common stock exceeds 275% of the conversion price for a specified period of time and subject to certain conditions upon 10 days prior written notice at a cash redemption price equal to the then outstanding principal amount, plus any accrued but unpaid interest. On or after October 31, 2023, the PHC Notes are redeemable by the Company upon 10 days prior written notice at a cash redemption price equal to the then outstanding principal amount, plus any accrued but unpaid interest, plus a call premium of 130% if redeemed at least six months prior to the Maturity Date or a call premium of 125% if redeemed within six months of the Maturity Date. ​ The Note Purchase Agreement contains customary terms and covenants, including financial covenants, such as operating within an approved budget and achieving minimum revenue and liquidity targets, and negative covenants, such as limitations on indebtedness, liens, mergers, asset transfers, certain investing activities and other matters customarily restricted in such agreements. Most of these restrictions are subject to certain minimum thresholds and exceptions. The Note Purchase Agreement also contains customary events of default, after which the PHC Notes become due and payable immediately, including defaults related to payment compliance, material inaccuracy of representations and warranties, covenant compliance, material adverse changes, bankruptcy and insolvency proceedings, cross defaults to certain other agreements, judgments against the Company, change of control or delisting events, termination of any guaranty, governmental approvals, and lien priority. ​ The Company also has the option to sell and issue PHC up to $15.0 million of convertible preferred stock on or before December 31, 2022 (the “PHC Option”), contingent upon obtaining approval for the 180-day Eversense product for marketing in the United States before such date. This purchased put option represents a freestanding financial instrument and is recognized as an asset in the Company’s consolidated balance sheets at fair value on the date of issuance and subject to impairment testing in each reporting period prior to the options exercise or expiration. The Company acknowledges that while the purchased put option is subject to impairment testing, there is no explicit guidance regarding how impairment should be assessed and measured for the PHC purchased put option. As such, the measurement alternative in ASC 321 for equity securities without readily determinable fair values can be applied by analogy to assess and measure impairment of the purchased put option. The Company developed an estimated fair value at September 30, 2021 to be $0.2 million, and an impairment loss of $0.5 million for the three months ended September 30, 2021, was recognized in net income as the difference between the fair value of the investment and its carrying amount. ​ The Note Purchase Agreement also contained several provisions requiring bifurcation as a separate derivative liability including an embedded conversion feature, mandatory prepayment upon event of default that constitutes a breach of the minimum revenue financial covenant, optional redemption upon an event of default, change in interest rate after PMA approval and default interest upon an event of default. The Company recorded the fair value of the embedded features in the amount of $25.8 million as a derivative liability in the Company’s consolidated balance sheets in accordance with ASC Topic 815, Derivatives and Hedging. The derivative is adjusted to fair value at each reporting period, with the change in the fair value recorded in change in fair value of derivatives that is a component of other income (expense) in the Company’s consolidated statement of operations and comprehensive loss. ​ In connection with the issuance of the Note Purchase Agreement, the Company incurred $2.9 million in debt issuance costs and debt discounts. The associated debt issuance costs were recorded as a contra liability in the amount of $1.4 million and are deferred and amortized as additional interest expense over the term of the notes. ​ 2025 Notes ​ In July 2019, the Company issued $82.0 million in aggregate principal amount of senior convertible notes that will mature on January 15, 2025 (the “2025 Notes”), unless earlier repurchased or converted. The 2025 Notes are convertible, at the option of the holders, into shares of the Company’s common stock, at an initial conversion rate of 757.5758 shares per $1,000 principal amount of the 2025 Notes (equivalent to an initial conversion price of approximately $1.32 per share). ​ The 2025 Notes also contained an embedded conversion option requiring bifurcation as a separate derivative liability, along with the fundamental change make-whole provision and the cash settled fundamental make-whole shares provision. The derivative is adjusted to fair value at each reporting period, with the change in the fair value recorded to other income (expense) in the Company’s consolidated statement of operations and comprehensive loss. ​ In connection with the Exchange on April 24, 2020, $24.0 million aggregate principal of the Company’s outstanding 2025 Notes held by Highbridge were exchanged for $15.7 million of Second Lien Notes, (i) 11,026,086 shares of common stock, (ii) warrants to purchase up to 4,500,000 shares of common stock at an exercise price of $0.66 per share, and (iii) $0.3 million in accrued and unpaid interest on the 2025 Notes being exchanged. This transaction modified the original 2025 Notes outstanding with Highbridge and resulted in $13.2 million of deferred issuance fees and debt discounts associated with the exchanged 2025 Notes being transferred as a discount to the Second Lien Notes. ​ For the nine months ended September 30, 2021, there were conversions of $6.5 million of outstanding principal amount of the 2025 notes for 4,924,998 shares of common stock. ​ 2023 Notes ​ In the first quarter of 2018, the Company issued $53.0 million in aggregate principal amount of senior convertible notes due February 1, 2023 (the “2023 Notes”). In July 2019, the Company used the net proceeds from the issuance of the 2025 Notes to repurchase $37.0 million aggregate principal amount of the outstanding 2023 Notes. Each $1,000 of principal of the 2023 Notes is initially convertible into 294.1176 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $3.40 per share, subject to adjustment upon the occurrence of specified events. ​ The Company bifurcated the embedded conversion option, along with the interest make-whole provision and make-whole fundamental change provision as a derivative liability. The derivative is adjusted to fair value at each reporting period, with the change in the fair value recorded in change in fair value of derivatives that is a component of other income (expense) in the Company’s consolidated statement of operations and comprehensive loss. ​ The following carrying amounts were outstanding under the Company’s notes payable as of September 30, 2021 and December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ ​ ​ Principal ($) ​ Debt Discount ($) ​ Issuance Costs ($) ​ Carrying Amount ($) ​ ​ ​ 2023 Notes 15,700 ​ (1,824) ​ - ​ 13,876 ​ ​ ​ 2025 Notes 51,199 ​ (21,742) ​ (364) ​ 29,093 ​ ​ ​ PHC Notes 35,000 ​ (19,610) ​ (1,198) ​ 14,192 ​ ​ ​ PPP Loan 5,113 ​ - ​ - ​ 5,113 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ Principal ($) ​ Debt Discount ($) ​ Issuance Costs ($) ​ Carrying Amount ($) ​ ​ ​ 2023 Notes 15,700 ​ (2,755) ​ - ​ 12,945 ​ ​ ​ 2025 Notes 57,700 ​ (28,276) ​ (431) ​ 28,993 ​ ​ ​ PHC Notes 36,312 ​ (22,237) ​ (1,359) ​ 12,716 ​ ​ ​ PPP Loan 5,763 ​ - ​ - ​ 5,763 ​ ​ ​ ​ Interest expense related to the notes payable for the three and nine months ended September 30, 2021 was as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, 2021 ​ Effective Interest Rate ​ Interest ($) ​ Debt Discount and Fees ($) ​ Issuance Costs ($) ​ Loss on Extinguishment ($) ​ Total Interest Expense ($) 2023 Notes 5.25% ​ 206 ​ 318 ​ - ​ - ​ 524 2025 Notes 5.25% ​ 672 ​ 1,152 ​ 19 ​ - ​ 1,843 PHC Notes 9.50% ​ 831 ​ 950 ​ 58 ​ - ​ 1,839 PPP Loan 1.00% ​ 15 ​ - ​ - ​ - ​ 15 Total ​ ​ 1,724 ​ 2,420 ​ 77 ​ - ​ 4,221 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, 2021 ​ Effective Interest Rate ​ Interest ($) ​ Debt Discount and Fees ($) ​ Issuance Costs ($) ​ Loss on Extinguishment ($) ​ Total Interest Expense ($) 2023 Notes 5.25% ​ 618 ​ 931 ​ - ​ - ​ 1,549 2025 Notes 5.25% ​ 2,044 ​ 3,362 ​ 56 ​ 3,183 ​ 8,645 PHC Notes 9.50% ​ 2,456 ​ 2,627 ​ 161 ​ - ​ 5,244 PPP Loan 1.00% ​ 44 ​ - ​ - ​ - ​ 44 Total ​ ​ 5,162 ​ 6,920 ​ 217 ​ 3,183 ​ 15,482 ​ The following are the scheduled maturities of the Company’s notes payable as of September 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ 2021 (remaining three months) $ 2,191 ​ 2022 ​ ​ 2,922 2023 ​ 15,700 ​ 2024 ​ ​ 35,000 ​ Thereafter ​ ​ 51,199 ​ Total $ 107,012 ​ ​

Stockholders' Deficit

Stockholders' Deficit	9 Months Ended
	Sep. 30, 2021
Stockholders' Deficit
Stockholders' Deficit	9. Stockholders’ Deficit ​ In November 2019, the Company entered into an Open Market Sale Agreement with Jefferies LLC which allows the Company to issue and sell up to $50.0 million in gross proceeds of its common stock. During the nine months ended September 30, 2021 the Company sold 12,830,333 shares of common stock under the Open Market Sale Agreement, resulting in gross proceeds of $48.4 million. During the nine months ended September 30, 2020, the Company sold 175,289 shares of common stock under the Open Market Sale Agreement, resulting in gross proceeds of $0.1 million. ​ During the nine months ended September 30, 2021, in addition to the shares sold under the Open Market Sale Agreement above, the Company sold 99,740,259 shares of common stock, of which 59,740,259 shares of common stock were sold in the Offering and 40,000,000 shares of common stock were sold in the Registered Direct Offering. During the nine months ended September 30, 2020, the Company did not sell any shares of common stock, other than the shares sold under the Open Market Sale Agreement. For additional information on the Offering and the Registered Direct Offering, see Note 2—Liquidity and Capital Resources. ​ ​

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Stock-Based Compensation
Stock-Based Compensation	10. Stock-Based Compensation ​ 2015 Plan ​ In December 2015, the Company adopted the 2015 Equity Incentive Plan (the “2015 Plan”), under which incentive stock options, non-qualified stock options and restricted stock units may be granted to the Company’s employees and certain other persons, such as officers and directors, in accordance with the 2015 Plan provisions. In February 2016, the Company’s Board of Directors adopted, and the Company’s stockholders approved, an Amended and Restated 2015 Equity Incentive Plan (the “amended and restated 2015 Plan”), which became effective on March 17, 2016. The Company’s board of directors may terminate the amended and restated 2015 Plan at any time. Options granted under the amended and restated 2015 Plan expire ten years after the date of grant. ​ Pursuant to the amended and restated 2015 Plan, the number of shares of the Company’s common stock reserved for issuance automatically increases on January 1 of each year, ending on January 1, 2026, by 3.5% of the total number of shares of its common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by its board of directors. As of September 30, 2021, 9,276,073 shares remained available for grant under the amended and restated 2015 Plan. ​ Inducement Plan ​ On May 30, 2019, the Company adopted the Senseonics Holdings, Inc. Inducement Plan (the “Inducement Plan”), pursuant to which the Company reserved 1,800,000 shares of the Company’s common stock for issuance. The only persons eligible to receive grants of awards under the Inducement Plan are individuals who satisfy the standards for inducement grants in accordance with NYSE American Company Guide Section 711(a), including individuals who were not previously an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to such persons entering into employment with the Company. An “Award” is any right to receive the Company’s common stock pursuant to the Inducement Plan, consisting of non-statutory options, restricted stock unit awards and other equity incentive awards. As of September 30, 2021, 735,375 shares remained available for grant under the Inducement Plan. ​ 2016 Employee Stock Purchase Plan ​ In February 2016, the Company adopted the 2016 Employee Stock Purchase Plan, (the “2016 ESPP”). The 2016 ESPP became effective on March 17, 2016. The maximum number of shares of common stock that may be issued under the 2016 ESPP was initially 800,000 shares and automatically increases on January 1 of each year, ending on and including January 1, 2026, by 1.0% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year; provided, however, the Board of Directors may act prior to the first day of any calendar year to provide that there will be no January 1 increase in the share reserve for such calendar year or that the increase in the share reserve for such calendar year will be a lesser number of shares of common stock. At September 30, 2021 there were 8,670,753 shares of common stock available for issuance under the 2016 ESPP. ​ The 2016 ESPP permits participants to purchase shares of the Company’s common stock through payroll deductions of up to 15% of their earnings. Unless otherwise determined by the administrator, the purchase price of the shares will be 85% of the lower of the fair market value of common stock on the first day of an offering or on the date of purchase. Participants may end their participation at any time and deductions not yet used in a purchase are refundable upon employment termination. The Company initiated its first 2016 ESPP offering period on August 1, 2019 and new offering periods occur every six months thereafter, each consisting of two purchase periods of six months in duration ending on or about January 31st and July 31st of each year. A participant may only be in one offering at a time. On February 1, 2020, there were 566,573 shares purchased in connection with the initial offering period. The 2016 ESPP contains an offering reset provision whereby if the fair market value of a share on offering date of an ongoing offering is less than or equal to the fair market value of a share on a new offering date, the ongoing offering will terminate immediately after the purchase date and rolls over to the new offering. ​ The 2016 ESPP is considered compensatory for financial reporting purposes. ​ 1997 Plan ​ On May 8, 1997, the Company adopted the 1997 Stock Option Plan (the “1997 Plan”), under which incentive stock options, non-qualified stock options, and restricted stock awards may be granted to the Company’s employees and certain other persons in accordance with the 1997 Plan provisions. Approximately 2,115,534 shares of the Company’s common stock underlying options have vested under the 1997 Plan. Upon the effectiveness of the 2015 Plan, the Company no longer grants any awards under the 1997 Plan. ​

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Measurements
Fair Value Measurements	11. Fair Value Measurements ​ The following table represents the fair value hierarchy of the Company’s financial assets and liabilities measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ Total Level 1 Level 2 Level 3 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds⁽¹⁾ ​ $ 43,818 ​ $ 43,818 ​ $ — ​ $ — ​ Corporate debt securities ​ ​ 40,085 ​ ​ — ​ ​ 40,085 ​ ​ — ​ Commercial paper ​ ​ 62,336 ​ ​ — ​ ​ 62,336 ​ ​ — ​ Government and agency securities ​ ​ 20,050 ​ ​ 20,050 ​ ​ — ​ ​ — ​ PHC Option ​ ​ 236 ​ ​ — ​ ​ — ​ ​ 236 ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Energy Capital Option ​ $ 91,097 ​ $ — ​ $ — ​ $ 91,097 ​ Embedded features of the 2023 Notes ​ ​ 9,492 ​ ​ — ​ ​ — ​ ​ 9,492 ​ Embedded features of the PHC Notes ​ ​ 195,727 ​ ​ — ​ ​ — ​ ​ 195,727 ​ Embedded features of the 2025 Notes ​ ​ 112,085 ​ ​ — ​ ​ 112,085 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ Total Level 1 Level 2 Level 3 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds⁽¹⁾ ​ $ 3 ​ $ 3 ​ $ — ​ $ — ​ PHC Option ​ ​ 1,886 ​ ​ — ​ ​ — ​ ​ 1,886 ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Energy Capital Option ​ $ 16,255 ​ $ — ​ $ — ​ $ 16,255 ​ Masters Option ​ ​ 23,479 ​ ​ — ​ ​ — ​ ​ 23,479 ​ Embedded features of the 2023 Notes ​ ​ 622 ​ ​ — ​ ​ — ​ ​ 622 ​ Embedded features of the PHC Notes ​ ​ 45,647 ​ ​ — ​ ​ — ​ ​ 45,647 ​ Embedded features of the 2025 Notes ​ ​ 15,850 ​ ​ — ​ ​ 15,850 ​ ​ — ​ ​ (1) Classified as cash and cash equivalents due to their short-term maturity ​ The following table provides a reconciliation of the beginning and ending net balances of items measured at fair value on a recurring basis that used significant unobservable inputs (Level 3) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 3 ​ Instruments December 31, 2020 ​ $ 84,117 Conversion of financial instruments ​ ​ (19,973) Loss on fair value adjustment of option ​ ​ 74,848 Loss on change in fair value of derivatives ​ ​ 158,951 Gain on extinguishment of option ​ ​ (3,513) Financial asset impairment cost ​ ​ 1,650 September 30, 2021 ​ $ 296,080 ​ The recurring Level 3 fair value measurements of the embedded features of the notes payable include the following significant unobservable inputs at September 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ 2023 Notes ​ PHC Notes ​ Unobservable Inputs ​ Assumptions ​ Assumptions ​ Risky (bond) rate 30.0 % 15.0 % Stock price volatility 95.0 % 95.0 % Probabilities of conversion provisions ​ 5.0 - 90.0 % 5.0 - 75.0 % Time period until maturity (yrs) 0.50 - 1.34 ​ 0.50 - 3.08 ​ Dividend yield — % — % ​

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Taxes
Income Taxes	12. Income Taxes ​ The Company has no t recorded any tax provision or benefit for the nine months ended September 30, 2021 or September 30, 2020. The Company has provided a valuation allowance for the full amount of its net deferred tax assets since realization of any future benefit from deductible temporary differences, NOL carryforwards and research and development credits is not more-likely-than-not to be realized at September 30, 2021 and December 31, 2020. ​ On March 27, 2020, Congress enacted the CARES Act, as amended by the Flexibility Act, to provide certain relief as a result of the COVID-19 pandemic. The enactment of the CARES Act did not result in any material adjustments to the Company’s income tax provision or net deferred tax assets for the nine months ended September 30, 2021.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions
Related Party Transactions	13. Related Party Transactions ​ Ascensia, through the ownership interests of its parent company, PHC, has a noncontrolling ownership interest in the Company. Ascensia also has representation on the Company’s board of directors. and the amount due from Ascensia as of September 30, 2021 was $3.5 million. At September 30, 2021, the Company had estimated replacement obligations under warranties in the amount of $1.7 million.

Reclassification of Prior Year

Reclassification of Prior Year Presentation	9 Months Ended
	Sep. 30, 2021
Reclassification of Prior Year Presentation
Reclassification of Prior Year Presentation	14. Reclassification of Prior Year Presentation ​ Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations. An adjustment has been made to the Consolidated Statements of Cash Flows for the nine months ended September 30, 2020 ​

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events
Subsequent Events	​ 15. Subsequent Events ​ In November 2021, the Company entered into an Open Market Sale Agreement (the “2021 Sales Agreement”) with Jefferies LLC (“Jeffries”), under which the Company could offer and sell, from time to time at its sole discretion, shares of its common stock having an aggregate offering price of up to $150.0 million through Jeffries as its sales agent in an “at the market” offering. Jeffries will receive a commission up to 3.0% of the gross proceeds of any common stock sold through Jeffries under the 2021 Sales Agreement. As of the date of this Quarterly Report on Form 10-Q, there have been no offer and sales of the Company’s common stock under the 2021 Sales Agreement.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation ​ The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Although the Company considers the disclosures in these unaudited consolidated financial statements to be adequate to make the information presented not misleading, certain information or footnote information normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted as permitted under the rules and regulations of the United States Securities and Exchange Commission (“SEC”). In the opinion of management, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair statement of financial position at September 30, 2021, and December 31, 2020, results of operations, comprehensive income (loss), and changes in stockholder’s equity (deficit) for the three and nine months ended September 30, 2021, and 2020 and cash flows for the nine months ended September 30, 2021, and 2020 have been included. The unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the SEC on March 5, 2021. The interim results for September 30, 2021, are not necessarily indicative of the results to be expected for the year ending December 31, 2021, or for any future interim periods. The consolidated financial statements reflect the accounts of Senseonics Holdings, Inc. and its wholly owned operating subsidiary Senseonics Incorporated.
Use of Estimates	Use of Estimates ​ The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenue and expenses during the reporting period. In the accompanying unaudited consolidated financial statements, estimates are used for, but not limited to, stock-based compensation, recoverability of long-lived assets, deferred taxes and valuation allowances, derivative assets and liabilities, obsolete inventory, warranty obligations, variable consideration related to revenue, depreciable lives of property and equipment, and accruals for clinical study costs, which are accrued based on estimates of work performed under contract. The Company considered COVID-19 related impacts to its estimates, as appropriate, within its unaudited condensed consolidated financial statements and there may be changes to those estimates in future periods due to the uncertainties surrounding the severity and duration of the COVID-19 pandemic. Actual results could differ from those estimates; however, management does not believe that such differences would be material.
Segment Information	Segment Information ​ The Company views its operations and manages its business in one segment, glucose monitoring products.
Comprehensive Loss	Comprehensive Loss ​ Comprehensive income (loss) comprises net income (loss) and other changes in equity that are excluded from net income (loss). For the three and nine months ended September 30, 2021, the Company’s comprehensive income (loss) included less than $0.1 million of other comprehensive income related to the unrealized gain on marketable securities. For the three and nine months ended September 30, 2020, the Company’s net loss equaled its comprehensive loss and, accordingly, no additional disclosure is presented. ​
Cash and Cash Equivalents	Cash and Cash Equivalents ​ The Company considers highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. These investments are carried at cost, which approximates fair value. Cash and cash equivalents consisted of the following as of the periods listed below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash ⁽ ¹ ⁾ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,393 ​ $ 18,002 ​ Money market funds ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 43,818 ​ ​ 3 ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 ​ (1) Includes overnight repurchase agreements
Restricted Cash	Restricted Cash ​ The Company’s restricted cash previously included pledged cash as collateral related to its credit card program with Silicon Valley Bank (“SVB”). The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statement of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 Restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ 200 Cash, cash equivalents and restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,205
Long-lived Assets	Long-lived Assets Management reviews long-lived assets, including property and equipment and right-of-use assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of the long-lived asset is measured by a comparison of the carrying amount of the asset to future undiscounted net cash flows expected to be generated by the asset. If the undiscounted cash flows are less than the carrying amount, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets. Management identified an indicator of impairment for a right of use asset and recorded an immaterial expense for the nine months ended September 30, 2021. There was no impairment recorded for the three months ended September 30, 2021.
Warranty Obligation	Warranty Obligation The Company provides a warranty of one year on its smart transmitters. Additionally, the Company may also replace Eversense system components that do not function in accordance with the product specifications. Estimated replacement costs are recorded at the time of shipment as a charge to cost of sales in the consolidated statement of operations and are developed by analyzing product performance data and historical replacement experience, including comparing actual replacements to revenue. At September 30, 2021, and December 31, 2020, the warranty reserve for both periods was $0.6 million. The following table provides a reconciliation of the change in estimated warranty liabilities for the nine months ended September 30, 2021 and for the twelve months ended December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2021 2020 Balance at beginning of the period ​ $ 646 ​ $ 2,197 Provision for warranties during the period ​ ​ 760 ​ ​ (266) Settlements made during the period ​ ​ (844) ​ ​ (1,285) Balance at end of the period ​ $ 562 ​ $ 646
Revenue	Revenue The Company recognizes revenue in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company generates revenue from sales of its Eversense CGM system and related components at a fixed price to third-party distributors in the European Union and to strategic fulfillment partners in the United States, and a combination of fixed and variable prices to its strategic partner, Ascensia (collectively, “Customers”), who then resell the products to health care providers and patients. The Company is paid for its sales directly to the Customers, regardless of whether or not the Customers resell the products to health care providers and patients. Customer contracts do not include the right to return unless there is a product issue, in which case the Company may provide replacement product. Product conformity guarantees do not create additional performance obligations and are accounted for as warranty obligations in accordance with guarantee and loss contingency accounting guidance. Revenue is recognized, at a point in time, when the Customers obtain control of the product based upon the delivery terms as defined in the contract, at an amount that reflects the consideration which is expected to be received in exchange for the product. Contracts with the Customers include performance obligations for supply of goods and the performance obligation is typically satisfied upon transfer of control of the product. Distribution contracts may also contain requirements for training and customer service support; however, these are not assessed as performance obligations given the activities are considered immaterial in the context of the contract. The payment terms and conditions of the Customers vary, but the Company is typically paid within 60 days of invoicing subsequent to the Customers obtaining control of the Company’s product. The Company’s contracts contain variable consideration such as prompt-pay discounts, tier-volume price discounts and for the Ascensia commercial agreement, revenue share. Variable consideration, such as discounts and prompt-pay incentives, are treated as a reduction in revenue and variable consideration, such as revenue share is treated as an addition in revenue when the product sale is recognized. The amount of variable consideration that is included in the transaction price may be constrained and is included in revenue only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period, when the uncertainty associated with the variable consideration is subsequently resolved. Estimating variable consideration and the related constraint requires the use of significant management judgement. Depending on the variable consideration, the Company estimates the expected value based on the terms of the agreements, historical data, geographic mix, reimbursement rates, and market conditions. The Company’s estimates used in determining the variable consideration on a sale transaction may be adjusted each reporting period depending on actual results, provided a change does not reflect a modification to the original contract. Contract assets consist of trade receivables and unbilled receivables from customers and are recorded at net realizable value. Unbilled receivables relate to the revenue share variable consideration from the Ascensia commercial agreement. ​ Concentration of Revenue and Customers ​ For the three months ended September 30, 2021, the Company derived 92% of its total revenue from one customer, Ascensia. For the three months ended September 30, 2020, the Company derived 33% of its total revenue from one customer, Roche Diabetes Care GmbH. For the nine months ended September 30, 2021, the Company derived 88% of its total revenue from one customer, Ascensia. For the nine months ended September 30, 2020, the Company derived 29% of its total revenue from one customer, Roche Diabetes Care GmbH. Revenues for these corresponding periods represent purchases for sensors, transmitters and miscellaneous Eversense system components. ​ Revenue by Geographic Region ​ The following table sets forth net revenue derived from the Company’s two primary geographical markets, the United States and outside of the United States, based on the geographic location to which the Company delivers the product, for the three and nine months ended September 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2021 ​ ​ September 30, 2021 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 2,928 ​ 82.9 % ​ $ 7,771 ​ 80.4 % United States ​ 604 ​ 17.1 ​ ​ ​ 1,896 ​ 19.6 ​ Total $ 3,532 ​ 100.0 % ​ $ 9,667 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2020 ​ ​ September 30, 2020 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 258 ​ 33.6 % ​ $ 325 ​ 30.5 % United States ​ 509 ​ 66.4 ​ ​ ​ 739 ​ 69.5 ​ Total $ 767 ​ 100.0 % ​ $ 1,064 ​ 100.0 %
Marketable Securities	Marketable Securities Marketable securities consist of commercial paper, corporate debt securities, asset backed securities and government and agency securities. The Company’s investments are classified as available for sale. Such securities are carried at fair value, with any unrealized holding gains or losses reported, net of any tax effects reported, as accumulated other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, are included in consolidated results of operations. A decline in the market value of any available for sale security below cost that is deemed to be other-than-temporary results in a reduction in fair value, which is charged to earnings in that period, and a new cost basis for the security is established. Dividend and interest income is recognized when earned. The cost of securities sold is calculated using the specific identification method. The Company classifies all available-for-sale marketable securities with maturities greater than one year from the balance sheet date as non-current assets.
Accounts Receivable	Accounts Receivable ​ Accounts receivable consist of amounts due from the Company’s Customers and are recorded at net realizable value, which may include reductions for allowances for doubtful accounts at the time potential collection risk is identified or for promotional or prompt-pay discounts offered. The Company does not have a history of collectability concerns and no allowance for uncollectible accounts was recorded as of September 30, 2021, however, an immaterial allowance for uncollectible accounts was recorded as of December 31, 2020. Accounts receivable as of September 30, 2021 included unbilled accounts receivable of $2.0 million. The Company expects to invoice and collect all unbilled accounts receivable within 12 months.
Net Income (Loss) per Share	Net Income (Loss) per Share ​ Basic net income per share attributable to common stockholders is calculated by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares outstanding during the period and, when dilutive, potential common share equivalents. Basic net loss per share is computed by dividing net loss available to common stockholders by the weighted average number of shares of common stock outstanding during the period. ​ Potentially dilutive common shares consist of shares issuable from restricted stock units, warrants, and our convertible notes. Potentially dilutive common shares issuable upon vesting of restricted stock units and exercise of stock options and warrants are determined using the average share price for each period under the treasury stock method. Potentially dilutive common shares issuable upon conversion of our convertible notes are determined using the if converted method. In periods of net loss, all potentially dilutive common shares are excluded from the computation of the diluted net loss per share for those periods, as the effect would be anti-dilutive. ​ The following table sets forth the computation of basic and diluted net income per share for the periods shown: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2021 2020 ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) ​ 42,914 ​ (23,428) ​ (386,907) ​ (73,536) Impact of conversion of dilutive securities ​ 1,385 ​ - ​ - ​ - ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive Net income (loss) ​ 44,299 ​ (23,428) ​ (386,907) ​ (73,536) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) per share ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ 0.10 ​ (0.10) ​ (0.93) ​ (0.33) Diluted ​ 0.08 ​ (0.10) ​ (0.93) ​ (0.33) ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted average shares outstanding ​ 445,378,308 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060 Dilutive potential common stock outstanding ​ ​ ​ ​ ​ ​ ​ ​ Stock-based awards ​ 15,520,414 ​ - ​ - ​ - 2023 Notes ​ 4,617,646 ​ - ​ - ​ - 2025 Notes ​ 39,689,142 ​ - ​ - ​ - PHC Notes ​ 65,348,857 ​ - ​ - ​ - Warrants ​ 11,206,148 ​ - ​ - ​ - Diluted weighted average shares outstanding ​ 581,760,516 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060 ​ For the nine months ended September 30, 2021, as well as for the three and nine months ended September 30, 2020, the Company operated at a loss. Accordingly, all potentially dilutive shares were considered antidilutive, and basic and diluted EPS are the same. ​ Outstanding anti-dilutive securities not included in the diluted net income per share attributable to common stockholders calculations were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2021 2020 ​ 2021 ​ 2020 Stock-based awards ​ 1,949,958 ​ 27,972,959 ​ 28,502,846 ​ 27,972,959 2023 Notes ​ — ​ 6,672,500 ​ 4,617,646 ​ 6,672,500 2025 Notes ​ — ​ 44,429,624 ​ 39,689,142 ​ 44,429,624 PHC Notes ​ — ​ 65,359,000 ​ 65,757,177 ​ 65,359,000 Second Lien Notes ​ — ​ 18,085,140 ​ — ​ 18,085,140 Warrants ​ 116,581 ​ 9,696,581 ​ 13,177,822 ​ 9,696,581 Total anti-dilutive shares outstanding ​ 2,066,539 ​ 172,215,804 ​ 151,744,633 ​ 172,215,804
Exit or Disposal Costs	Exit or Disposal Costs ​ Costs associated with exit or disposal activities, such as restructuring, sale or termination of a line of business, the closure of business activities in a particular location, the relocation of business activities, changes in management structure and a fundamental reorganization that affects the nature and focus of operations, are recognized and measured initially at their fair values during the period in which an obligation meets the definition of a liability. There were no exit or disposal activities for the three and nine months ended September 30, 2021. The Company’s workforce reduction on March 26, 2020 did not permit continuation of service past March 31, 2020 and associated one-time employee termination benefit costs in the amount of $1.4 million were paid and recorded in the Company’s accompanying unaudited consolidated financial statements for the nine months ended September 30, 2020. ​ ​
Recent Accounting Pronouncements	Recent Accounting Pronouncements ​ Recently Adopted ​ In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes ​ Not Yet Adopted ​ In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments ​ In August 2020, the FASB issued ASU 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contract in Entity’s Own Equity (Subtopic 815-40).

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Summary of Significant Accounting Policies
Schedule of cash and cash equivalents	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash ⁽ ¹ ⁾ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,393 ​ $ 18,002 ​ Money market funds ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 43,818 ​ ​ 3 ​ Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 ​ (1) Includes overnight repurchase agreements
Schedule of restricted cash	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ ​ ​ ​ ​ 2021 2020 Cash and cash equivalents ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,005 Restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ 200 Cash, cash equivalents and restricted cash ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 46,211 ​ $ 18,205
Schedule of estimated warranty liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2021 2020 Balance at beginning of the period ​ $ 646 ​ $ 2,197 Provision for warranties during the period ​ ​ 760 ​ ​ (266) Settlements made during the period ​ ​ (844) ​ ​ (1,285) Balance at end of the period ​ $ 562 ​ $ 646
Schedule of revenue by geographic region	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2021 ​ ​ September 30, 2021 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 2,928 ​ 82.9 % ​ $ 7,771 ​ 80.4 % United States ​ 604 ​ 17.1 ​ ​ ​ 1,896 ​ 19.6 ​ Total $ 3,532 ​ 100.0 % ​ $ 9,667 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ September 30, 2020 ​ ​ September 30, 2020 ​ ​ ​ ​ % ​ ​ ​ ​ % ​ (Dollars in thousands) Amount ​ of Total ​ ​ Amount ​ of Total ​ Revenue, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outside of the United States $ 258 ​ 33.6 % ​ $ 325 ​ 30.5 % United States ​ 509 ​ 66.4 ​ ​ ​ 739 ​ 69.5 ​ Total $ 767 ​ 100.0 % ​ $ 1,064 ​ 100.0 %
Schedule of computation of basic and diluted net income per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2021 2020 ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) ​ 42,914 ​ (23,428) ​ (386,907) ​ (73,536) Impact of conversion of dilutive securities ​ 1,385 ​ - ​ - ​ - ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive Net income (loss) ​ 44,299 ​ (23,428) ​ (386,907) ​ (73,536) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) per share ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ 0.10 ​ (0.10) ​ (0.93) ​ (0.33) Diluted ​ 0.08 ​ (0.10) ​ (0.93) ​ (0.33) ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted average shares outstanding ​ 445,378,308 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060 Dilutive potential common stock outstanding ​ ​ ​ ​ ​ ​ ​ ​ Stock-based awards ​ 15,520,414 ​ - ​ - ​ - 2023 Notes ​ 4,617,646 ​ - ​ - ​ - 2025 Notes ​ 39,689,142 ​ - ​ - ​ - PHC Notes ​ 65,348,857 ​ - ​ - ​ - Warrants ​ 11,206,148 ​ - ​ - ​ - Diluted weighted average shares outstanding ​ 581,760,516 ​ 236,519,812 ​ 414,128,283 ​ 220,250,060
Schedule of anti-dilutive shares which have been excluded from the computation of diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2021 2020 ​ 2021 ​ 2020 Stock-based awards ​ 1,949,958 ​ 27,972,959 ​ 28,502,846 ​ 27,972,959 2023 Notes ​ — ​ 6,672,500 ​ 4,617,646 ​ 6,672,500 2025 Notes ​ — ​ 44,429,624 ​ 39,689,142 ​ 44,429,624 PHC Notes ​ — ​ 65,359,000 ​ 65,757,177 ​ 65,359,000 Second Lien Notes ​ — ​ 18,085,140 ​ — ​ 18,085,140 Warrants ​ 116,581 ​ 9,696,581 ​ 13,177,822 ​ 9,696,581 Total anti-dilutive shares outstanding ​ 2,066,539 ​ 172,215,804 ​ 151,744,633 ​ 172,215,804

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Marketable Securities
Schedule of marketable securities available for sale	Marketable securities available for sale, were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ ​ ​ Gross ​ Gross ​ Estimated ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Market ​ Cost Gains Losses Value Commercial Paper ​ $ 62,336 ​ ​ — ​ ​ — ​ $ 62,336 Corporate debt securities ​ $ 40,084 ​ ​ 5 ​ ​ (4) ​ $ 40,085 Asset backed securities ​ $ 27,869 ​ ​ 5 ​ ​ (4) ​ $ 27,870 Government and agency securities ​ $ 24,630 ​ ​ 5 ​ ​ (5) ​ $ 24,630 Total ​ $ 154,919 ​ $ 15 ​ $ (13) ​ $ 154,921
Schedule of maturities of marketable securities	The following are the scheduled maturities as of September 30, 2021 (in thousands): ​ ​ ​ ​ ​ 2021 (remaining three months) $ 4,999 2022 ​ ​ 149,922 2023 ​ — 2024 ​ ​ — Thereafter ​ ​ — Total $ 154,921

Inventory, net (Tables)

Inventory, net (Tables)	9 Months Ended
	Sep. 30, 2021
Inventory, net
Schedule of Inventory, net	Inventory, net of reserves, consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 2020 Finished goods $ 1,927 $ 203 Work-in-process ​ 4,513 ​ 2,626 Raw materials ​ 1,438 ​ 2,452 Total ​ $ 7,878 ​ $ 5,281

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Prepaid Expenses and Other Current Assets
Schedule of prepaid expenses and other current assets	Prepaid expenses and other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 Contract manufacturing⁽¹⁾ ​ $ 2,431 ​ $ 3,324 Interest receivable ​ 378 ​ — Insurance ​ ​ 266 ​ ​ 50 IT and software ​ 266 ​ 150 Research and development ​ ​ 115 ​ ​ — Rent ​ ​ 105 ​ ​ 102 Other ​ 171 ​ 148 Total prepaid expenses and other current assets ​ $ 3,732 ​ $ 3,774 ​ (1) Includes deposits to contract manufacturers for manufacturing process .

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Accrued Expenses and Other Current Liabilities
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 Compensation and benefits ​ $ 3,010 ​ $ 4,344 Interest on notes payable ​ 2,098 ​ 1,773 Professional and administration services ​ ​ 1,945 ​ ​ 880 Product warranty and replacement obligations ​ ​ 1,783 ​ ​ 646 Contract manufacturing ​ ​ 1,629 ​ ​ 1,421 Research and development ​ 1,454 ​ 842 Sales and marketing services ​ 1,149 ​ 615 Operating lease ​ ​ 875 ​ ​ 794 Other ​ ​ 42 ​ ​ 151 Patient access programs ​ ​ — ​ ​ 208 Total accrued expenses and other current liabilities ​ $ 13,985 ​ $ 11,674

Notes Payable, Preferred Stoc_2

Notes Payable, Preferred Stock and Stock Purchase Warrants (Tables)	9 Months Ended
	Sep. 30, 2021
Notes Payable, Preferred Stock and Stock Purchase Warrants
Schedule of carrying amounts outstanding under the Company's notes payable	The following carrying amounts were outstanding under the Company’s notes payable as of September 30, 2021 and December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ ​ ​ Principal ($) ​ Debt Discount ($) ​ Issuance Costs ($) ​ Carrying Amount ($) ​ ​ ​ 2023 Notes 15,700 ​ (1,824) ​ - ​ 13,876 ​ ​ ​ 2025 Notes 51,199 ​ (21,742) ​ (364) ​ 29,093 ​ ​ ​ PHC Notes 35,000 ​ (19,610) ​ (1,198) ​ 14,192 ​ ​ ​ PPP Loan 5,113 ​ - ​ - ​ 5,113 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ Principal ($) ​ Debt Discount ($) ​ Issuance Costs ($) ​ Carrying Amount ($) ​ ​ ​ 2023 Notes 15,700 ​ (2,755) ​ - ​ 12,945 ​ ​ ​ 2025 Notes 57,700 ​ (28,276) ​ (431) ​ 28,993 ​ ​ ​ PHC Notes 36,312 ​ (22,237) ​ (1,359) ​ 12,716 ​ ​ ​ PPP Loan 5,763 ​ - ​ - ​ 5,763 ​ ​ ​
Schedule of interest expense related to the notes payable	Interest expense related to the notes payable for the three and nine months ended September 30, 2021 was as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, 2021 ​ Effective Interest Rate ​ Interest ($) ​ Debt Discount and Fees ($) ​ Issuance Costs ($) ​ Loss on Extinguishment ($) ​ Total Interest Expense ($) 2023 Notes 5.25% ​ 206 ​ 318 ​ - ​ - ​ 524 2025 Notes 5.25% ​ 672 ​ 1,152 ​ 19 ​ - ​ 1,843 PHC Notes 9.50% ​ 831 ​ 950 ​ 58 ​ - ​ 1,839 PPP Loan 1.00% ​ 15 ​ - ​ - ​ - ​ 15 Total ​ ​ 1,724 ​ 2,420 ​ 77 ​ - ​ 4,221 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, 2021 ​ Effective Interest Rate ​ Interest ($) ​ Debt Discount and Fees ($) ​ Issuance Costs ($) ​ Loss on Extinguishment ($) ​ Total Interest Expense ($) 2023 Notes 5.25% ​ 618 ​ 931 ​ - ​ - ​ 1,549 2025 Notes 5.25% ​ 2,044 ​ 3,362 ​ 56 ​ 3,183 ​ 8,645 PHC Notes 9.50% ​ 2,456 ​ 2,627 ​ 161 ​ - ​ 5,244 PPP Loan 1.00% ​ 44 ​ - ​ - ​ - ​ 44 Total ​ ​ 5,162 ​ 6,920 ​ 217 ​ 3,183 ​ 15,482
Schedule of future maturities	The following are the scheduled maturities of the Company’s notes payable as of September 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ 2021 (remaining three months) $ 2,191 ​ 2022 ​ ​ 2,922 2023 ​ 15,700 ​ 2024 ​ ​ 35,000 ​ Thereafter ​ ​ 51,199 ​ Total $ 107,012 ​

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Measurements
Schedule of fair value hierarchy of the Company's financial assets and liabilities measured at fair value on a recurring basis	The following table represents the fair value hierarchy of the Company’s financial assets and liabilities measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ Total Level 1 Level 2 Level 3 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds⁽¹⁾ ​ $ 43,818 ​ $ 43,818 ​ $ — ​ $ — ​ Corporate debt securities ​ ​ 40,085 ​ ​ — ​ ​ 40,085 ​ ​ — ​ Commercial paper ​ ​ 62,336 ​ ​ — ​ ​ 62,336 ​ ​ — ​ Government and agency securities ​ ​ 20,050 ​ ​ 20,050 ​ ​ — ​ ​ — ​ PHC Option ​ ​ 236 ​ ​ — ​ ​ — ​ ​ 236 ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Energy Capital Option ​ $ 91,097 ​ $ — ​ $ — ​ $ 91,097 ​ Embedded features of the 2023 Notes ​ ​ 9,492 ​ ​ — ​ ​ — ​ ​ 9,492 ​ Embedded features of the PHC Notes ​ ​ 195,727 ​ ​ — ​ ​ — ​ ​ 195,727 ​ Embedded features of the 2025 Notes ​ ​ 112,085 ​ ​ — ​ ​ 112,085 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ Total Level 1 Level 2 Level 3 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds⁽¹⁾ ​ $ 3 ​ $ 3 ​ $ — ​ $ — ​ PHC Option ​ ​ 1,886 ​ ​ — ​ ​ — ​ ​ 1,886 ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Energy Capital Option ​ $ 16,255 ​ $ — ​ $ — ​ $ 16,255 ​ Masters Option ​ ​ 23,479 ​ ​ — ​ ​ — ​ ​ 23,479 ​ Embedded features of the 2023 Notes ​ ​ 622 ​ ​ — ​ ​ — ​ ​ 622 ​ Embedded features of the PHC Notes ​ ​ 45,647 ​ ​ — ​ ​ — ​ ​ 45,647 ​ Embedded features of the 2025 Notes ​ ​ 15,850 ​ ​ — ​ ​ 15,850 ​ ​ — ​ ​ (1) Classified as cash and cash equivalents due to their short-term maturity
Schedule of changes in the fair value of Level 3 derivative liability measured at fair value	The following table provides a reconciliation of the beginning and ending net balances of items measured at fair value on a recurring basis that used significant unobservable inputs (Level 3) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 3 ​ Instruments December 31, 2020 ​ $ 84,117 Conversion of financial instruments ​ ​ (19,973) Loss on fair value adjustment of option ​ ​ 74,848 Loss on change in fair value of derivatives ​ ​ 158,951 Gain on extinguishment of option ​ ​ (3,513) Financial asset impairment cost ​ ​ 1,650 September 30, 2021 ​ $ 296,080
Schedule of assumptions used to determine fair value	The recurring Level 3 fair value measurements of the embedded features of the notes payable include the following significant unobservable inputs at September 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ 2023 Notes ​ PHC Notes ​ Unobservable Inputs ​ Assumptions ​ Assumptions ​ Risky (bond) rate 30.0 % 15.0 % Stock price volatility 95.0 % 95.0 % Probabilities of conversion provisions ​ 5.0 - 90.0 % 5.0 - 75.0 % Time period until maturity (yrs) 0.50 - 1.34 ​ 0.50 - 3.08 ​ Dividend yield — % — %

Liquidity and Capital Resourc_2

Liquidity and Capital Resources (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 31, 2021	Jan. 27, 2021	Jan. 26, 2021	Jan. 21, 2021	Jan. 17, 2021	Nov. 09, 2020	Aug. 09, 2020	Apr. 24, 2020	Jun. 30, 2021	Nov. 30, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 14, 2020
Net Income (Loss)											$ 42,914	$ (23,428)	$ (386,907)	$ (73,536)		$ (175,200)	$ (115,500)	$ (94,000)
Accumulated deficit											(1,035,418)		(1,035,418)			$ (648,511)
Issuance of common stock, net													200,440	$ (86)
Cash, cash equivalents and marketable securities											$ 201,100		$ 201,100
Common stock, par value per share (in dollars per share)											$ 0.001		$ 0.001			$ 0.001
Highbridge Loan Agreement
Aggregate principal amount								$ 15,000
Shares issued								1,500,000
PHC Notes
Aggregate principal amount							$ 35,000				$ 35,000		$ 35,000			$ 36,312
Financing fee shares issued							2,941,176
Conversion price							$ 0.54
Common stock, par value per share (in dollars per share)							$ 0.001
Ascensia | PHC Notes
Aggregate principal amount							$ 35,000
Energy Capital, LLC
Cash and cash equivalents and other available credit				$ 8,000
Energy Capital, LLC | Maximum
Aggregate principal amount of convertible preferred equity				$ 4,000
Energy Capital, LLC | Forecast | Maximum
Aggregate principal amount of convertible preferred equity															$ 12,000
Share price															$ 0.25
Convertible Preferred Equity
Amount of possible additional debt principal amount							$ 15,000
Convertible Preferred Equity | Masters Capital
Shares issued							3,000
Convertible Preferred Equity | Energy Capital, LLC
Aggregate principal amount of convertible preferred equity						$ 12,000
Price per share (in dollars per share)				$ 1,000
Collaboration and commercialization agreement term						24 months
Convertible Preferred Equity | Energy Capital, LLC | Forecast
Share price															$ 1,000
Threshold redemption period of temporary equity															6 months
Conversion price															$ 0.3951
Series A Preferred Stock
Aggregate principal amount of convertible preferred equity													$ 42,756
Series A Preferred Stock | Masters Capital
Shares issued	22,783
Price per share (in dollars per share)	$ 1,000						$ 1,000												$ 1,000
Conversion price	$ 0.476
Proceeds from issuance of stock	$ 22,800
Series A Preferred Stock | Masters Capital | Maximum
Shares issued							27,000
Purchasers
Shares issued					40,000,000
Price per share (in dollars per share)					$ 1.25
Common stock, par value per share (in dollars per share)					$ 0.001
Net proceeds					$ 46,100
Proceeds from issuance of stock					$ 50,000
Overallotment | Public Offering
Shares issued		7,792,207		51,948,052
Price per share (in dollars per share)				$ 1.925
Underwriters Share Price				$ 1.799875
Net proceeds			$ 106,100
Open Market Sale Agreement
Shares issued									12,830,333				12,830,333	175,289
Proceeds from issuance of stock									$ 48,400				$ 48,400	$ 100
Open Market Sale Agreement | Maximum
Issuance of common stock, net										$ 50,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Segment Information (Details)	9 Months Ended
	Sep. 30, 2021segment
Segment Information
Number of operating segments	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash	$ 2,393	$ 2,393	$ 18,002
Money market funds	43,818	43,818	3
Cash and cash equivalents	46,211	46,211	$ 18,005
Unrealized gain on marketable securities	18	2
Maximum
Cash and Cash Equivalents, at Carrying Value [Abstract]
Unrealized gain on marketable securities	$ 100	$ 100

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 46,211	$ 18,005
Restricted cash		200
Cash, cash equivalents, and restricted cash	$ 46,211	$ 18,205	$ 26,392	$ 95,938

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Long-lived assets (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2021USD ($)
Property and Equipment, net
Impairment	$ 0

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Warranty Reserve (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Reconciliation of the change in estimated warranty liabilities
Warranty term	1 year
Balance at beginning of the period	$ 646	$ 2,197
Provision for warranties during the period		(266)
Provision for warranties during the period	760
Settlements made during the period	(844)	(1,285)
Balance at end of the period	$ 562	$ 646

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Concentration of Revenue and Customers (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)itemcustomer	Sep. 30, 2020USD ($)customer	Sep. 30, 2021USD ($)itemcustomer	Sep. 30, 2020USD ($)customer
Estimated total revenue from major customers
Number of geographical markets | item	2		2
Revenues	$ 3,532	$ 767	$ 9,667	$ 1,064
Payment period			60 days
Revenue | Ascensia
Estimated total revenue from major customers
Number of customers | customer	1		1
Revenue | Roche
Estimated total revenue from major customers
Number of customers | customer		1		1
Revenue | Customer Concentration Risk | Ascensia
Estimated total revenue from major customers
Percentage of total revenue	92.00%		88.00%
Revenue | Customer Concentration Risk | Roche
Estimated total revenue from major customers
Percentage of total revenue		33.00%		29.00%
Revenue | Geographic Concentration Risk
Estimated total revenue from major customers
Percentage of total revenue	100.00%	100.00%	100.00%	100.00%
Revenues	$ 3,532	$ 767	$ 9,667	$ 1,064
Outside of the United States | Revenue | Geographic Concentration Risk
Estimated total revenue from major customers
Percentage of total revenue	82.90%	33.60%	80.40%	30.50%
Revenues	$ 2,928	$ 258	$ 7,771	$ 325
United States | Revenue | Geographic Concentration Risk
Estimated total revenue from major customers
Percentage of total revenue	17.10%	66.40%	19.60%	69.50%
Revenues	$ 604	$ 509	$ 1,896	$ 739

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Accounts Receivable (Details) $ in Millions	Sep. 30, 2021USD ($)
Accounts Receivable
Allowance for uncollectible accounts	$ 0
Unbilled accounts receivable	$ 2

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ 42,914	$ (23,428)	$ (386,907)	$ (73,536)	$ (175,200)	$ (115,500)	$ (94,000)
Impact of conversion of dilutive securities	1,385
Dilutive Net income (loss)	$ 44,299	$ (23,428)	$ (386,907)	$ (73,536)
Net income (loss) per share
Basic	$ 0.10	$ (0.10)	$ (0.93)	$ (0.33)
Diluted	$ 0.08	$ (0.10)	$ (0.93)	$ (0.33)
Basic weighted average shares outstanding	445,378,308	236,519,812	414,128,283	220,250,060
Dilutive potential common stock outstanding
Warrants	11,206,148
Diluted weighted average shares outstanding	581,760,516	236,519,812	414,128,283	220,250,060
Net Loss per Share
Total anti-dilutive shares outstanding	2,066,539	172,215,804	151,744,633	172,215,804
Stock-based awards
Dilutive potential common stock outstanding
Stock-based awards	15,520,414
Net Loss per Share
Total anti-dilutive shares outstanding	1,949,958	27,972,959	28,502,846	27,972,959
2023 Notes
Dilutive potential common stock outstanding
Convertible Notes	4,617,646
Net Loss per Share
Total anti-dilutive shares outstanding		6,672,500	4,617,646	6,672,500
2025 Notes
Dilutive potential common stock outstanding
Convertible Notes	39,689,142
Net Loss per Share
Total anti-dilutive shares outstanding		44,429,624	39,689,142	44,429,624
PHC Notes
Dilutive potential common stock outstanding
Convertible Notes	65,348,857
Net Loss per Share
Total anti-dilutive shares outstanding		65,359,000	65,757,177	65,359,000
Second Lien Notes
Net Loss per Share
Total anti-dilutive shares outstanding		18,085,140		18,085,140
Warrants
Net Loss per Share
Total anti-dilutive shares outstanding	116,581	9,696,581	13,177,822	9,696,581

Summary of Significant Accou_12

Summary of Significant Accounting Policies - Exit or Disposal Costs (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)
Summary of Significant Accounting Policies
Benefit costs	$ 1.4

Marketable Securities - AFS Deb

Marketable Securities - AFS Debt Securities (Details) $ in Thousands	Sep. 30, 2021USD ($)
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	$ 154,919
Gross Unrealized Gains	15
Gross Unrealized Losses	(13)
Estimated Market Value	154,921
Commercial paper
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	62,336
Estimated Market Value	62,336
Corporate debt securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	40,084
Gross Unrealized Gains	5
Gross Unrealized Losses	(4)
Estimated Market Value	40,085
Asset backed Securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	27,869
Gross Unrealized Gains	5
Gross Unrealized Losses	(4)
Estimated Market Value	27,870
Government and agency securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	24,630
Gross Unrealized Gains	5
Gross Unrealized Losses	(5)
Estimated Market Value	$ 24,630

Marketable Securities - AFS D_2

Marketable Securities - AFS Debt Securities - Maturities (Details) $ in Thousands	Sep. 30, 2021USD ($)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
2021 (remaining three months)	$ 4,999
2022	149,922
Total	$ 154,921

Inventory, net (Details)

Inventory, net (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Finished goods	$ 1,927	$ 1,927		$ 203
Work-in-process	4,513	4,513		2,626
Raw materials	1,438	1,438		2,452
Total	7,878	7,878		$ 5,281
Inventory Valuation and Obsolescence
Inventory adjustments included in cost of sales
Cost	$ 1,800	$ 1,800	$ 15,100

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Prepaid Expenses and Other Current Assets
Contract manufacturing	$ 2,431	$ 3,324
Interest receivable	378
Insurance	266	50
IT and software	266	150
Research and development	115
Rent	105	102
Other	171	148
Total prepaid expenses and other current assets	$ 3,732	$ 3,774

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Expenses and Other Current Liabilities
Compensation and benefits	$ 3,010	$ 4,344
Interest on notes payable	2,098	1,773
Professional and administration services	1,945	880
Product warranty and replacement obligations	1,783	646
Contract manufacturing	1,629	1,421
Research and development	1,454	842
Sales and marketing services	1,149	615
Operating lease	875	794
Other	42	151
Patient access programs		208
Total accrued expenses and other current liabilities	$ 13,985	$ 11,674

Notes Payable, Preferred Stoc_3

Notes Payable, Preferred Stock and Stock Purchase Warrants (Details) $ / shares in Units, $ in Thousands	Jan. 31, 2021USD ($)$ / sharesshares	Jan. 21, 2021USD ($)$ / shares	Nov. 09, 2020USD ($)$ / shares	Aug. 09, 2020USD ($)$ / sharesshares	Apr. 24, 2020USD ($)$ / sharesshares	Apr. 22, 2020USD ($)	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	May 09, 2021$ / sharesshares	Aug. 14, 2020$ / sharesshares
Debt Instrument [Line Items]
Loss on extinguishment								$ (3,183)
Notes payable
Derivative assets							$ 236	236		$ 1,886
Carrying Amount							57,161	57,161		57,216
Derivative liabilities							$ 317,304	$ 317,304		$ 62,119
Common stock, par value per share (in dollars per share) | $ / shares							$ 0.001	$ 0.001		$ 0.001
Amount used to retire existing loans								$ 650	$ 66,050
Highbridge Loan Agreement
Debt Instrument [Line Items]
Final payment fee, notes					$ 17,600
Loss on extinguishment					(700)
Notes payable
Principal amount					$ 15,000
Shares issued | shares					1,500,000
Exchange Agreement with Highbridge
Debt Instrument [Line Items]
Warrants to purchase shares | shares					4,500,000
Exercise price of warrant (in dollars per share) | $ / shares					$ 0.66
Notes payable
Shares issued | shares					11,026,086
Accrued and unpaid interest					$ 300
PHC Notes
Notes payable
Principal amount				$ 35,000			$ 35,000	$ 35,000		$ 36,312
Interest rate (as a percent)				9.50%			8.00%	8.00%
Carrying Amount							$ 14,192	$ 14,192		12,716
Debt issuance costs and discounts				$ 1,400
Fair value of the embedded conversion option				$ 25,800
Effective Interest Rate							9.50%	9.50%
Financing fee shares issued | shares				2,941,176
Common stock, par value per share (in dollars per share) | $ / shares				$ 0.001
Debt discount of financing fee shares				$ 1,500
Conversion rate				1,867.4136
Conversion price | $ / shares				$ 0.54
Conversion of Stock, Amount Issued				$ 15,000
Issuance costs incurred				2,900			$ 1,198	$ 1,198		1,359
Amount of principal which is converted to shares				$ 1
PHC Notes | Debt Redemption on or After October 31, 2022
Notes payable
Threshold percentage of stock trigger				275.00%
Notice period				10 days
PHC Notes | Debt Redemption on or After October 31, 2023
Notes payable
Notice period				10 days
PHC Notes | Debt Redemption Six Months Prior to Maturity Date
Notes payable
Call premium percentage				130.00%
PHC Notes | Debt Redemption Within Six Months of Maturity Date
Notes payable
Call premium percentage				125.00%
2025 Notes | Exchange Agreement with Highbridge
Notes payable
Principal amount					24,000
Deferred issuance costs and debt discounts					13,200
PPP Loan
Notes payable
Amount received from loan funding						$ 5,800
Principal amount							5,113	5,113		5,763
Interest rate (as a percent)						1.00%
Note term						2 years
Carrying Amount							$ 5,113	$ 5,113		5,763
Effective Interest Rate							1.00%	1.00%
PPP Loan | Silicon Valley Bank
Notes payable
Principal amount						$ 5,800
Second Lien Notes | Exchange Agreement with Highbridge
Notes payable
Principal amount					$ 15,700
Original debt conversion amount										$ 15,700
Debt converted, Shares issued | shares										42,776,936
PHC Option | Put option
Notes payable
Derivative assets							$ 200	$ 200
Loss on fair value adjustment of derivatives							(500)
Energy Capital Facility
Debt Instrument [Line Items]
Exercise price of warrant (in dollars per share) | $ / shares											$ 0.3951
Notes payable
Deferred issuance costs and debt discounts			$ 7,600
Period to purchase stock			24 months
Cash Cash Equivalents and Other Available Credit Threshold		$ 8,000
Derivative liabilities			$ 4,200				$ 91,100	$ 91,100
Energy Capital Facility | Maximum
Debt Instrument [Line Items]
Warrants to purchase shares | shares											10,000,000
Series B Preferred Stock | Energy Capital Facility
Notes payable
Preferred stock value			$ 12,000
Share price for debt conversion | $ / shares		$ 1,000
Period to purchase stock		6 months
Daily limit		$ 4,000
Conversion price | $ / shares			$ 0.3951
Series B Preferred Stock | Energy Capital Facility | Minimum
Notes payable
Share price for debt conversion | $ / shares		$ 0.25
Series B Preferred Stock | Energy Capital Facility | Maximum
Notes payable
Preferred stock value			$ 12,000
Series A Preferred Stock
Notes payable
Debt converted, Shares issued | shares								25,783
Gain on extinguishment								$ 3,500
Series A Preferred Stock | Masters Capital
Notes payable
Shares issued | shares	22,783
Conversion price | $ / shares	$ 0.476
Amount of principal which is converted to shares	$ 1
Number of shares issued and sold | shares				27,000								3,000
Price per share (in dollars per share) | $ / shares	$ 1,000			$ 1,000								$ 1,000
Additional shares issued | shares	22,783
Gross proceeds from stock	$ 22,800
Series A Preferred Stock | Masters Capital | Maximum
Notes payable
Shares issued | shares				27,000

Notes Payable, Preferred Stoc_4

Notes Payable, Preferred Stock and Stock Purchase Warrants - Term Notes Payable (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Jul. 31, 2019USD ($)$ / shares	Mar. 31, 2018USD ($)$ / shares	Sep. 30, 2021USD ($)shares	Dec. 31, 2020USD ($)
Long term debt
Loss on extinguishment of debt and issuance of debt			$ (3,183)
2023 Notes
Long term debt
Principal amount		$ 53,000	15,700	$ 15,700
Conversion rate (per $1,000 of principal)		294.1176
Conversion price (in dollars per share) | $ / shares		$ 3.40
Repurchase amount	$ 37,000
Amount of principal which is converted to shares		$ 1
2025 Notes
Long term debt
Principal amount	$ 82,000		51,199	$ 57,700
Conversion rate (per $1,000 of principal)	757.5758
Conversion price (in dollars per share) | $ / shares	$ 1.32
Amount of principal which is converted to shares	$ 1
Original debt conversion amount			$ 6,500
Debt converted, Shares issued | shares			4,924,998
Loss on extinguishment of debt and issuance of debt			$ (3,183)

Notes Payable, Preferred Stoc_5

Notes Payable, Preferred Stock and Stock Purchase Warrants - Carrying amount of notes payable (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Aug. 09, 2020	Jul. 31, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Carrying Amount	$ 57,161	$ 57,216
2023 Notes
Debt Instrument [Line Items]
Aggregate principal amount	15,700	15,700			$ 53,000
Debt Discount	(1,824)	(2,755)
Carrying Amount	13,876	12,945
2025 Notes
Debt Instrument [Line Items]
Aggregate principal amount	51,199	57,700		$ 82,000
Debt Discount	(21,742)	(28,276)
Issuance costs	(364)	(431)
Carrying Amount	29,093	28,993
PHC Notes
Debt Instrument [Line Items]
Aggregate principal amount	35,000	36,312	$ 35,000
Debt Discount	(19,610)	(22,237)
Issuance costs	(1,198)	(1,359)	$ (2,900)
Carrying Amount	14,192	12,716
PPP Loan
Debt Instrument [Line Items]
Aggregate principal amount	5,113	5,763
Carrying Amount	$ 5,113	$ 5,763

Notes Payable, Preferred Stoc_6

Notes Payable, Preferred Stock and Stock Purchase Warrants - Interest expense (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)
Long term debt
Interest	$ 1,724	$ 5,162
Debt Discount & Fees	2,420	6,920
Issuance Costs	77	217
Loss on extinguishment of debt		3,183
Total Interest Expense	$ 4,221	$ 15,482
2023 Notes
Long term debt
Effective Interest Rate	5.25%	5.25%
Interest	$ 206	$ 618
Debt Discount & Fees	318	931
Total Interest Expense	$ 524	$ 1,549
2025 Notes
Long term debt
Effective Interest Rate	5.25%	5.25%
Interest	$ 672	$ 2,044
Debt Discount & Fees	1,152	3,362
Issuance Costs	19	56
Loss on extinguishment of debt		3,183
Total Interest Expense	$ 1,843	$ 8,645
PHC Notes
Long term debt
Effective Interest Rate	9.50%	9.50%
Interest	$ 831	$ 2,456
Debt Discount & Fees	950	2,627
Issuance Costs	58	161
Total Interest Expense	$ 1,839	$ 5,244
PPP Loan
Long term debt
Effective Interest Rate	1.00%	1.00%
Interest	$ 15	$ 44
Total Interest Expense	$ 15	$ 44

Notes Payable, Preferred Stoc_7

Notes Payable, Preferred Stock and Stock Purchase Warrants - Scheduled Maturities (Details) $ in Thousands	Sep. 30, 2021USD ($)
Scheduled maturities
2021 (remaining three months)	$ 2,191
2022	2,922
2023	15,700
2024	35,000
Thereafter	51,199
Total	$ 107,012

Stockholders' Deficit (Details)

Stockholders' Deficit (Details) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Jun. 30, 2021	Nov. 30, 2019	Sep. 30, 2021	Sep. 30, 2020
Class of Stock [Line Items]
Net Proceeds			$ 200,440	$ (86)
Open Market Sale Agreement
Class of Stock [Line Items]
Shares issued	12,830,333		12,830,333	175,289
Proceeds from issuance of common stock, net	$ 48,400		$ 48,400	$ 100
Number of additional shares issued			99,740,259
Open Market Sale Agreement | Maximum
Class of Stock [Line Items]
Net Proceeds		$ 50,000
Offering
Class of Stock [Line Items]
Shares issued			59,740,259
Registered Direct Offering
Class of Stock [Line Items]
Shares issued			40,000,000

Stock-Based Compensation (Detai

Stock-Based Compensation (Details)	Feb. 01, 2020shares	Feb. 29, 2016shares	Dec. 31, 2015	Sep. 30, 2021itemshares	May 30, 2019shares
2015 Equity Incentive Plan
Stock-based compensation
Expiration period			10 years
Automatic annual increase in shares authorized, percent of common stock outstanding				3.50%
Shares available for grant				9,276,073
1997 Stock Option Plan
Stock-based compensation
Options vested and expected to vest				2,115,534
Inducement Plan
Stock-based compensation
Shares available for grant				735,375
Total shares that may be issued					1,800,000
2016 Employee Stock Purchase Plan
Stock-based compensation
Shares available for grant		800,000		8,670,753
Share increase (as a percent)		1.00%
Payroll deductions for ESPP participants (as a percent)				15.00%
Percentage on share price issued				85.00%
Offering period duration				6 months
Purchase periods | item				2
Stock issued	566,573

Fair Value Measurements - Recur

Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Nov. 09, 2020
Fair Value Measurements
Cash and cash equivalents	$ 46,211	$ 18,005
Marketable securities	154,921
Derivative assets	236	1,886
Derivative liabilities	317,304	62,119
Energy Capital Facility
Fair Value Measurements
Derivative liabilities	91,100		$ 4,200
Recurring | Embedded conversion option | 2023 Notes
Fair Value Measurements
Derivative liabilities	9,492	622
Recurring | Embedded conversion option | 2025 Notes
Fair Value Measurements
Derivative liabilities	112,085	15,850
Recurring | Embedded conversion option | PHC Notes
Fair Value Measurements
Derivative liabilities	195,727	45,647
Recurring | Call Option | Masters Capital
Fair Value Measurements
Derivative liabilities		23,479
Recurring | Money market funds
Fair Value Measurements
Cash and cash equivalents	43,818	3
Recurring | Corporate debt securities
Fair Value Measurements
Marketable securities	40,085
Recurring | Commercial paper
Fair Value Measurements
Marketable securities	62,336
Recurring | Government and agency securities
Fair Value Measurements
Marketable securities	20,050
Recurring | PHC Option
Fair Value Measurements
Derivative assets	236	1,886
Recurring | Put Or Call Option | Energy Capital Facility
Fair Value Measurements
Derivative liabilities	91,097	16,255
Recurring | Level 1 | Money market funds
Fair Value Measurements
Cash and cash equivalents	43,818	3
Recurring | Level 1 | Government and agency securities
Fair Value Measurements
Marketable securities	20,050
Recurring | Level 2 | Embedded conversion option | 2025 Notes
Fair Value Measurements
Derivative liabilities	112,085	15,850
Recurring | Level 2 | Corporate debt securities
Fair Value Measurements
Marketable securities	40,085
Recurring | Level 2 | Commercial paper
Fair Value Measurements
Marketable securities	62,336
Recurring | Level 3
Reconciliation of items measured at fair value on a recurring basis that used significant unobservable inputs (Level 3)
Balance at the beginning of the period	84,117
Conversion of financial instruments	(19,973)
Loss on fair value adjustment of option	74,848
Loss on change in fair value of derivatives	158,951
Gain on extinguishment of option	(3,513)
Financial asset impairment cost	1,650
Balance at the end of the period	296,080
Recurring | Level 3 | Embedded conversion option | 2023 Notes
Fair Value Measurements
Derivative liabilities	9,492	622
Recurring | Level 3 | Embedded conversion option | PHC Notes
Fair Value Measurements
Derivative liabilities	195,727	45,647
Recurring | Level 3 | Call Option | Masters Capital
Fair Value Measurements
Derivative liabilities		23,479
Recurring | Level 3 | PHC Option
Fair Value Measurements
Derivative assets	236	1,886
Recurring | Level 3 | Put Or Call Option | Energy Capital Facility
Fair Value Measurements
Derivative liabilities	$ 91,097	$ 16,255

Fair Value Measurements - Valua

Fair Value Measurements - Valuation Assumptions (Details) - Recurring - Level 3	Sep. 30, 2021
2023 Notes | Risky (bond) rate
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.300
2023 Notes | Stock price volatility
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.950
2023 Notes | Probabilities of conversion provisions | Minimum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.050
2023 Notes | Probabilities of conversion provisions | Maximum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.900
2023 Notes | Time period until maturity | Minimum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.50
2023 Notes | Time period until maturity | Maximum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	1.34
PHC Notes | Risky (bond) rate
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.150
PHC Notes | Stock price volatility
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.950
PHC Notes | Probabilities of conversion provisions | Minimum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.050
PHC Notes | Probabilities of conversion provisions | Maximum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.750
PHC Notes | Time period until maturity | Minimum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	0.50
PHC Notes | Time period until maturity | Maximum
Fair value valuation assumptions
Embedded Derivative Liability, Measurement Input	3.08

Income Taxes - Tax Provision (D

Income Taxes - Tax Provision (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Income Taxes
Income tax provision	$ 0	$ 0

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related party transactions
Revenue	$ 3,256	$ 253	$ 8,471	$ 303
Due from related party	3,549		3,549		$ 2,421
Ascensia
Related party transactions
Revenue			8,500
Due from related party	3,500		3,500
Replacement obligations	$ 1,700		$ 1,700

Reclassification of Prior Yea_2

Reclassification of Prior Year Presentation (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Reclassification [Line Items]
Inventory	$ 2,597,000	$ (12,645,000)
Revision of Prior Period, Reclassification, Adjustment
Reclassification [Line Items]
Provision for inventory obsolescence and net realizable value		(9,441,000)
Inventory		$ (9,441,000)

Subsequent Events - (Details)

Subsequent Events - (Details) - Open Market Sale Agreement - Subsequent Event $ in Millions	1 Months Ended
	Nov. 30, 2021USD ($)
Subsequent Event [Line Items]
Maximum offering price under sales agreement	$ 150
Commission rate (as a percentage)	3.00%