SecProbe.io

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						March 10, 2005

Mail Stop 03-06

Andrew P. Rasdal
President and Chief Executive Officer
DexCom, Inc.
5555 Oberlin Drive
San Diego, California 92121

Re:	DexCom, Inc.
	Amendment no. 2 to Registration Statement on Form S-1
	Filed March 2, 2005
	File No. 333-122454

Dear Mr. Rasdal:

	We have reviewed your filing and have the following comments.
Where indicated, we think you should revise your document in
response
to these comments.  If you disagree, we will consider your
explanation as to why our comment is inapplicable or a revision is
unnecessary.  Please be as detailed as necessary in your
explanation.
In some of our comments, we may ask you to provide us with
supplemental information so we may better understand your
disclosure.
After reviewing this information, we may or may not raise
additional
comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter

Amendment no. 2 to Form S-1

Summary - Page 1
1. We note your response to comment 3 indicates that the company
believes that the endpoints designed for the trial of the short-
term
sensor were achieved.  Please clarify supplementally how the
selected
endpoints were determined.  Explain how achieving the endpoints in
the clinical trial supports the company`s belief that the clinical
trial will support a premarket approval application.  For example,
are the efficacy endpoints based on past FDA-approved product
results?
2. We note your response to comment 4.  Please revise to clarify
how
much longer after obtaining approval it will be before the company
begins to market its product commercially.
3. We note from the articles that you furnished supplementally
that a
relatively small percentage of individuals with diabetes
(approximately 14.6%) perform glucose self-monitoring one or more
times a day.  Expand the disclosure in the summary under "Market
Opportunity" and/or "Importance of Glucose Monitoring" and in the
Business section to disclose and quantify this point.  Revise the
disclosure to explain that the potential market for your products
would be considerably smaller than the figures given for the total
number of individuals with diabetes.  We also note your disclosure
on
page 4 that "patients may be unwilling to insert or implant a
sensor
in their body, especially if their current diabetes management
involves no more than two finger sticks per day."  Expand to
disclose
the percentage of diabetes patients whose diabetes management
involves more than two finger sticks per day, if known, or clarify
to
explain that testing more than twice per day is uncommon, as noted
in
the supplemental materials.  Refer to "Frequency of Blood Glucose
Monitoring in Relation to Glycemic Control in Patients with Type 2
Diabetes" at page 980.
4. We note your response to comment 7 and revised disclosure.
Please
expand the disclosure on page 3 of the Summary to briefly compare
your product with the products described under the caption
"Competition" on page 60.  For example, address the fact that at
least one of the continuous glucose monitors that has received FDA
approval employs non-invasive technology.

	The DexCom Solution - Page 3
5. In the fourth bullet, clarify that your first generation short-
term sensor will not eliminate the need for finger sticks.  We
note
your response to comment 21 and do not believe that saying in a
subsequent paragraph that your systems "may not be approved as
replacement devices for single-point finger stick devices" clearly
conveys the point that your product, at least initially, will not
eliminate the need for finger sticks, which the bullet paragraph
implies.

Risk Factors - Page 7

	Concentration of ownership among our existing directors . . .
-
Page 24
6. We note your response to comment 15.  Please expand your
disclosure to illustrate this risk through examples of proposals
and
actions these holders may support that would not be in the
interests
of unaffiliated shareholders.

Related Party Transactions - Page 85
7. We note your response to comment 30.  The spirit of Item 404 is
to
fully inform potential investors regarding related party
transactions
in connection with the formation of the registrant.  We believe
this
would include, for example, the equity issuances to founders and
for
technology that occurred in May, 1999, particularly if those who
received the securities are still employed by the registrant.
Please
revise.

Report of Independent Registered Public Accounting Firm - Page F-1

	Financial Statements
8. We refer to your response to prior comment 36.  We believe that
the audit report should include the additional language from AU
Section 9508.18.  We also understand that Ernst & Young`s national
office has consulted with the Office of the Chief Accountant of
the
Division of Corporation Finance with respect to this matter.
Please
revise.

*  *  *

      As appropriate, please amend your registration statement in
response to these comments.  You may wish to provide us with
marked
copies of the amendment to expedite our review.  Please furnish a
cover letter with your amendment that keys your responses to our
comments and provides any requested supplemental information.
Detailed cover letters greatly facilitate our review.  Please
understand that we may have additional comments after reviewing
your
amendment and responses to our comments.

      We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filings reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed decision.  Since the company and its management are in
possession of all facts relating to a company`s disclosure, they
are
responsible for the accuracy and adequacy of the disclosures they
have made.

      We direct your attention to Rules 460 and 461 regarding
requesting acceleration of a registration statement.  Please allow
adequate time after the filing of any amendment for further review
before submitting a request for acceleration.  Please provide this
request at least two business days in advance of the requested
effective date.

      You may contact Patrick Enunwaonye at (202) 824-5529 or Gary
Todd at (202) 942-2862 if you have questions regarding comments on
the financial statements and

related matters.  Please contact Eduardo Aleman at (202) 824-5661
or
me at (202) 942-1880 with any other questions.

      			Sincerely,

      			Peggy Fisher
						Assistant Director

cc (via facsimile):  Robert A. Freedman, Esq.
		      Charles Ruck, Esq.
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Andrew P. Rasdal
DexCom, Inc.
March 10, 2005
Page 1

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