Exhibit 32.01

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

PURSUANT TO

18 U.S.C SECTION 1350

The undersigned, Terrance H. Gregg, the President and Chief Executive Officer of DexCom, Inc. (the “Company”), pursuant to 18 U.S.C. §1350, hereby certifies that:

(i) the Quarterly Report on Form 10-Q for the period ended June 30, 2012 of the Company (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934.

(ii) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: August 6, 2012

/s/ Terrance H. Gregg

Terrance H. Gregg

Chief Executive Officer