FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * CARNEY SEAN   2. Issuer Name and Ticker or Trading Symbol DEXCOM INC [DXCM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O WARBURG PINCUS & CO., 466 LEXINGTON AVENUE, 10TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 09/21/2006 (Street) NEW YORK, NY 10017 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/21/2006   A   351 A $ 10.71 3,647 D   Common Stock 09/22/2006   A   120 A $ 10.46 3,767 D   Common Stock               2,221,626 I See Footnote (1) (2) Common Stock               37,779 I See Footnote (1) (2) Common Stock               26,615 I See Footnote (1) (2) Common Stock               6,442 I See Footnote (1) (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
CARNEY SEAN C/O WARBURG PINCUS & CO. 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK, NY 10017	X

Signatures

/s/ Jess Roper as Attorney-in-Fact for Sean Carney		09/25/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The stockholder is Warburg Pincus Private Equity VIII, L.P., a Delaware limited partnership, including two affiliated partnerships (collectively "WP VIII"). Warburg Pincus Partners LLC ("WP Partners LLC"), a New York limited liability company, a subsidiary of Warburg Pincus & Co. ("WP"), a New York general partnership, is the sole general partner of WP VIII. Warburg Pincus LLC ("WP LLC"), a New York limited liability company, manages WP VIII. By reason of the provisions of Rule 16a-1 of the Securities Exchange Act of 1934, as amended, WP VIII, WP Partners LLC, WP and WP LLC may be deemed to be the beneficial owners of the referenced shares. WP Partners LLC, WP and WP LLC disclaim beneficial ownership of such securities, except to the extent of any indirect pecuniary interest therein. Sean D. Carney is a parter of WP and a member and managing director of WP LLC.
(2)	Continued from Footnote 1: As such, Mr. Carney may be deemed to be the beneficial owner (within the meaning of Rule 16a-1 under the Securities Exchange Act of 1934) of an indeterminate portion of the securities beneficially owned by WP Partners LLC, WP, and WP LLC. Mr. Carney is also a member of the board of directors of the Issuer. Mr. Carney disclaims any beneficial ownership of securities reported herein as owned by WP VIII.

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