Exhibit 32.02

CERTIFICATION OF CHIEF FINANCIAL OFFICER

PURSUANT TO

18 U.S.C. SECTION 1350

The undersigned, Jess Roper, Chief Financial Officer of DexCom, Inc. (the “Company”), pursuant to 18 U.S.C. §1350, hereby certifies:

(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) and 15(d) of the Securities Exchange Act of 1934; and

(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/ Jess Roper

Jess Roper

Chief Financial Officer