DEXCOM INC — Director's Dealing 2015

May 11, 2015

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: DEXCOM INC (DXCM)
CIK: 0001093557
Period of Report: 2015-05-07

Reporting Person: GREGG TERRANCE H (Director, Executive Chairman)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2015-05-07	Common Stock	M	15000.0	$3.19	Acquired	445626	Direct
2015-05-07	Common Stock	S	15000.0	$67.59	Disposed	430626	Direct
2015-05-07	Common Stock	M	20000.0	$8.95	Acquired	450626	Direct
2015-05-07	Common Stock	S	20000.0	$67.48	Disposed	430626	Direct
2015-05-07	Common Stock	M	5000.0	$6.85	Acquired	435626	Direct
2015-05-07	Common Stock	S	5000.0	$67.5	Disposed	430626	Direct
2015-05-08	Common Stock	M	25000.0	$6.85	Acquired	455626	Direct
2015-05-08	Common Stock	S	25000.0	$67.9795	Disposed	430626	Direct
2015-05-08	Common Stock	M	26483.0	$3.19	Acquired	457109	Direct
2015-05-08	Common Stock	S	26483.0	$68.2088	Disposed	430626	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2015-05-07	Non-Qualified Stock Option (right to buy)	$3.19	M	15000.0	Disposed	2018-12-11	Common Stock (15000)	Direct
2015-05-08	Non-Qualified Stock Option (right to buy)	$3.19	M	26483.0	Disposed	2018-12-11	Common Stock (26483)	Direct
2015-05-07	Non-Qualified Stock Option (right to buy)	$6.85	M	5000.0	Disposed	2017-06-19	Common Stock (5000)	Direct
2015-05-08	Non-Qualified Stock Option (right to buy)	$6.85	M	25000.0	Disposed	2017-06-19	Common Stock (25000)	Direct
2015-05-07	Non-Qualified Stock Option (right to buy)	$8.95	M	20000.0	Disposed	2018-01-02	Common Stock (20000)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	11461	Indirect
Common Stock	522139	Indirect

Footnotes

F1: This transaction was executed in multiple trades at prices ranging from $67.50 to $67.66. 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.

F2: Included in this number are 202,580 unvested restricted stock units, 35,000 of which were granted on March 8, 2015 and will vest on March 8, 2016, 111,720 unvested restricted stock units granted on March 8, 2014, 5,078 of which shall vest each month through March 8, 2017, and 55,860 unvested restricted stock units granted on March 11, 2013, 5,078 of which shall vest each month through March 11, 2016.

F3: This transaction was executed in multiple trades at prices ranging from $67.26 to $68.12. 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.

F4: This transaction was executed in multiple trades at prices ranging from $67.88 to $68.01. 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.

F5: This transaction was executed in multiple trades at prices ranging from $67.96 to $68.53. 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.

F6: Shares are held by the Gregg Family Trust U/A/D 12/23/1998, with respect to which the reporting person is a trustee.