FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF 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 *   Leach Jacob Steven 2. Date of Event Requiring Statement (Month/Day/Year) 03/09/2017 3. Issuer Name and Ticker or Trading Symbol DEXCOM INC [DXCM] (Last) (First) (Middle) 6340 SEQUENCE DRIVE 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) SVP, Research & Development 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) SAN DIEGO, CA 92121 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 Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 105,933 (1) D   Common Stock 12,000 I Family Holdings (2) Common Stock 50,100 I by Spouse (3)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Incentive Stock Option (right to buy)	  (4)	12/11/2018	Common Stock	10,577	$ 3.19	D	Â
Incentive Stock Option (right to buy)	  (4)	10/02/2018	Common Stock	25,000	$ 5.92	D	Â
Incentive Stock Option (right to buy)	  (4)	11/20/2019	Common Stock	4,797	$ 7.27	D	Â
Incentive Stock Option (right to buy)	  (4)	05/19/2018	Common Stock	7,500	$ 7.63	D	Â
Incentive Stock Option (right to buy)	  (4)	02/18/2020	Common Stock	11,458	$ 9.78	D	Â
Non-Qualified Stock Option (right to buy)	  (4)	12/11/2018	Common Stock	1,923	$ 3.19	D	Â
Non-Qualified Stock Option (right to buy)	  (4)	11/20/2019	Common Stock	203	$ 7.27	D	Â
Non-Qualified Stock Option (right to buy)	  (4)	02/18/2020	Common Stock	8,542	$ 9.78	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Leach Jacob Steven 6340 SEQUENCE DRIVE SAN DIEGO, CA 92121	Â	Â	  SVP, Research & Development	Â

Signatures

By: Timothy O'Brien For: Jacob Leach		03/15/2017
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(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)	Included in this number are 57,800 unvested restricted stock units, 23,134 of which were granted on March 8, 2017 and shall vest through March 8, 2020, 21,333 of which were granted on March 8, 2016 shall vest through March 8, 2019 and 13,333 of which were granted on March 8, 2015 and shall vest through March 8, 2018.
(2)	Shares are held by the Gregg Family Grandchildren's Trust UAD 12/30/2010, with respect to which the reporting person's spouse is a trustee.
(3)	Shares are held by the Kyndra S. Leach Trust UAD 12/12/2012, with respect to which the reporting person's spouse is a trustee.
(4)	Shares subject to the option are fully vested and immediately exercisable.
  Remarks: CONFIRMING STATEMENT: This Statement confirms that the undersigned Jacob Leach, has authorized and designated Steve Pacelli, Kevin Sun, Patrick Murphy and Timothy O'Brien to execute and file on the undersigned's behalf all Forms 3, 4, and 5 (including any amendments thereto) that the undersigned may be required to file with the U.S. Securities and Exchange Commission as a result of the undersigned's ownership of or transactions in securities of DexCom, Inc. The authority of Steve Pacelli, Kevin Sun, Patrick Murphy and Timothy O'Brien under this Statement shall continue until the undersigned is no longer required to file Forms 3, 4, and 5 with regard to the undersigned's ownership of or transactions in securities of DexCom, Inc., unless earlier revoked in writing. The undersigned acknowledges that Steve Pacelli, Kevin Sun, Patrick Murphy and Timothy O'Brien are not assuming any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934. Date: March 14, 2017 /s/ JACOB LEACH Jacob Leach

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