United States securities and exchange commission logo May 5, 2022 Kevin R. Sayer President and Chief Executive Officer DEXCOM, INC. 6340 Sequence Drive San Diego, California 92121 Re: DEXCOM, INC. Form 10-K for the Fiscal Year Ended December 31, 2021 Filed on February 14, 2022 File No. 000-51222 Dear Mr. Sayer: We have completed our review of your filings. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Sincerely, Division of Corporation Finance Office of Life Sciences