EXHIBIT 1

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required on Schedule 13G need be filed with respect to ownership by each of the undersigned of shares of Common Stock of DexCom, Inc.

This Agreement may be executed in any number of counterparts, each of which shall be deemed an original.

Dated:  May 11, 2007.
THE TRAVELERS COMPANIES, INC.
By:	/s/ Bruce A. Backberg
	Bruce A. Backberg
Its:	Senior Vice President
ST. PAUL FIRE AND MARINE INSURANCE COMPANY
By:	/s/ Bruce A. Backberg
	Bruce A. Backberg
Its:	Senior Vice President
SPLIT ROCK PARTNERS, LLC
By:	/s/ Steven L.P. Schwen
	Steven L.P. Schwen
Its:	Chief Financial Officer

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