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 * KAHN BARBARA   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) 6340 SEQUENCE DRIVE 3. Date of Earliest Transaction (Month/Day/Year) 01/14/2019 (Street) SAN DIEGO, CA 92121 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 06/01/2018   J V 4,353 (1) D $ 0 3,449 (2) D   Common Stock 06/01/2018   J V 4,353 (1) A $ 0 27,448 (3) I by Trust Common Stock 01/14/2019   S   1,730 (4) D $ 141.1569 (5) 25,718 (3) I by Trust Common Stock 01/14/2019   S   3,558 (4) D $ 142.066 (6) 22,160 (3) I by Trust Common Stock 01/14/2019   S   5,343 (4) D $ 142.8326 (7) 16,817 (3) I by Trust

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
KAHN BARBARA 6340 SEQUENCE DRIVE SAN DIEGO, CA 92121	X

Signatures

By: Timothy O'Brien For: Barbara E. Kahn		01/16/2019
**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)	Shares were transferred from direct ownership to ownership under the Barbara Kahn TTEE Barbara Kahn Rev TRT DTD 6/26/96 & Robert Meyer TTEE Robert Meyer Rev Trst DTD 6/26/96, with respect to which the reporting person is a trustee.
(2)	Represents 3,449 unvested restricted stock units which were granted on June 1, 2018 and will vest on the earlier of the one year anniversary of the grant date or the date of DexCom Inc's 2019 Annual Meeting.
(3)	Shares are held by the Barbara Kahn TTEE Barbara Kahn Rev TRT DTD 6/26/96 & Robert Meyer TTEE Robert Meyer Rev Trst DTD 6/26/96, with respect to which the reporting person is a trustee.
(4)	On December 12, 2018, Ms. Kahn adopted a 10b5-1 Plan. This 10b5-1 Plan allows the orderly disposition of shares owned by Ms. Kahn. The exercise and sale of shares set forth above were pursuant to the 10b5-1 Plan.
(5)	This transaction was executed in multiple trades at prices ranging from $140.51 to $141.43. The price above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected.
(6)	This transaction was executed in multiple trades at prices ranging from $141.51 to $142.48. The price above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected.
(7)	This transaction was executed in multiple trades at prices ranging from $142.51 to $143.34. The price above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected.

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