SecProbe.io

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		February 25, 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.
	Registration Statement on Form S-1
      Filed on February 1, 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.

Form S-1
1. Please confirm that any preliminary prospectus you circulate
will
include all non-Rule 430A information.  This includes the price
range
and related information based on a bona fide estimate of the
public
offering price within that range, and other information that was
left
blank throughout the document.  Also, note that we may have
additional comments after you file this information.

Summary - Page 1
2. Revise this section to clarify the meaning of a premarket
approval
application and the regulatory agency that grants it.
3. Please advise us supplementally of the basis for your belief
that
the clinical trial of the company`s short-term system may support
a
premarket approval application by the end of the first half of
2005.
We may have further comments.
4. Please expand to discuss more specifically the length of time
you
anticipate it will take to obtain regulatory approval and begin to
market your products commercially.
5. Revise to provide a more balanced discussion of your market
opportunity with the negative aspects of your business.  Identify
the
registrant as a development stage company, and disclose that the
company has not generated any revenue since its inception and that
its products will need FDA approval before it will generate any
revenue in the future.
6. Please tell us supplementally the industry "sources" that
estimate
that people with diabetes test, on average, less than twice per
day
and project that the worldwide market for glucose monitoring
systems
is expected to grow at an annual compound rate of approximately
11.6%
by 2008.  Also, provide supplemental support for the industry data
attributed to the American Diabetes Association.
7. Under the caption "Limitations of Existing Glucose Monitoring
Products," we note you only discuss finger stick testing.  Expand
to
also discuss here and on page 42 how the products you are
developing
compare with the products described under the caption
"Competition"
on page 57 and any other existing glucose monitoring systems
currently on the market.
8. We note your reference to the March 2004 issue of Diabetes Care
citing the finding that patients in the clinical trial increased
the
time they spent at target blood glucose levels by 88%.  The
article
also discusses that these results could potentially be
attributable
to the high frequency of visits required for the study compared to
routine patient care.  Please revise to discuss this.  Also,
please
advise us supplementally if you are aware of any other
publications
discussing clinical trials of your long-term sensor and arriving
at
different conclusions that are not disclosed.
9. Whenever you refer to this peer-reviewed article in the filing,
clarify that DexCom sponsored the study, that two of the authors
of
the article have received consulting fees from DexCom for serving
on
its advisory board, and that all three authors received grant
research funds for conducting the study.

Risk Factors - Page 7

	If we are unable to successfully complete the pre-clinical
studies . . . - Page 10
10. We note your belief that the data and performance from each of
the last three clinical trials relating to the long-term system is
likely insufficient to support a Pre Market Approval application.
Please expand this discussion to include basis for this belief and
the impact on the company`s business strategy if ongoing clinical
trials do not support a PMA application.

	Our continuous glucose monitoring systems may never achieve
market acceptance even 	if we obtain regulatory approvals.   -
Page
11
11. You disclose that physicians tend to be slow to change their
medical treatment practices and may not recommend or prescribe the
company`s products until there is long-term clinical evidence them
to
alter their existing treatment method or until prominent
physicians
recommend the product.  To the extent known, please discuss this
tendency in terms of length of delay in gaining acceptance from
physicians.  For example, this could include a comparison of how
long
it took physicians to change current treatment regimes regarding
similar products such as Medtronic`s CGMS System Gold.

	We depend on clinical investigators and clinical sites to
enroll
patients in our clinical 	trials . . . - Page 12
12. In an appropriate location in the Business section, please
discuss the material terms, including duties, obligations and
deadlines, of your contracts with clinical investigators, clinical
sites or other third parties.  Please file any existing agreements
as
exhibits, or explain why you believe these are not required to be
filed.

	Our manufacturing operations are dependent upon third-party
suppliers . . . - Page 14
13. Please discuss the extent to which the company`s reliance on
single source outside manufacturers has in the past delayed or
impeded the company`s ability to meet its product requirements.

Risks Relating to this Offering - Page 22

	Changes in or interpretations of accounting rules and
regulations... - Page 22
14. Since the FASB published SFAS 123 (revised 2004) in December
2004, it appears that you should revise this discussion.  For
instance, your statements that the "standards have not been
finalized" and "the timing of a final statement has not been
established" appear inaccurate at this date.

Concentration of ownership among our existing directors . . . -
Page
23
15. Expand to give examples of proposals and actions these holders
may support that would not be in the interests of unaffiliated
shareholders.  Also briefly discuss the fiduciary duties of
directors
with regard to unaffiliated shareholders.

Capitalization - Page 28
16. "Cash and cash equivalents" is not a component of
capitalization
for purposes of this disclosure.  Please revise to delete that
line.

Dilution - Page 30
17. We note that the exercise prices of the company`s outstanding
options appear to be less than the initial offering price.  Please
disclose the additional dilution in pro forma net tangible book
value
per share to new investors assuming all options are exercised.
Also
disclose how the table at the top of page 31 would change assuming
exercise of all outstanding options and the warrant.  We may have
further comments when you complete the blanks in the disclosure.

Management`s Discussion and Analysis - Page 33

	Overview - Page 33
18. To the extent the company`s clinical trials have experienced
delays due to the factors cited, such as sensor performance and
manufacturing supply constraints, please discuss.

	Operating Capital and Capital Expenditure Requirements - Page
36
19. We note that you expect you have sufficient cash and cash
equivalents to meet anticipated requirements for the "foreseeable"
future.  Please be more specific and clarify whether you believe
these are sufficient to meet long term requirements.

Business - Page 40

	Our Technology Platform - Page 46
20. We note your discussion of your proprietary polymer membrane
technology designed to modify the foreign body response which,
historically, has blocked glucose from reaching the sensor and
hampers the implantable sensor`s ability to operate.  Please
expand
this disclosure to discuss whether the results from clinical
trials
indicate that the long term sensor has experienced similar
challenges, and how it has affected the sensor`s functionality.
We
note, for example, that in the various clinical trials several
sensors did not function adequately.

Short-Term Glucose Monitoring Sensor and Long-Term Glucose
Monitoring
Sensor - Page 47
21. We note that these products will not initially eliminate the
need
for finger sticks.  Revise the disclosure throughout the filing,
including in the summary, to make this point clear.  Also explain
in
the summary that the patient is required to insert the sensor
under
the skin every three days, and discuss any resulting negative or
adverse consequences.
	Long-Term Implantable Sensor Trials - Page 50
22. Revise to explain in plain English what the chart demonstrates
that is important to an investor and how your device compares with
the previously approved device.
23. At the top of page 51, clarify that this part of the study did
not compare your device to a previously approved device, if true.

	Competition - Page 57
24. Briefly explain how the non-invasive continuous glucose
monitoring products under development are designed to work, if
known.

	Manufacturing - Page 58
25. We note your disclosure that the company will need to increase
its manufacturing capacity by a significant factor over its
current
level to meet market demand, and that this will require the
investment of substantial additional funds.  Please discuss the
anticipated source of these additional funds and, to the extent
practicable, quantify the estimated funds needed.
26. Please discuss your plans to develop facilities adequate to
sustain manufacturing beyond the first year of commercial
production.

	Government Regulation - Page 61
27. Please provide the disclosure required by Item 101(c)(1)(xii)
of
Regulation S-K.  We note that the company is subject to federal,
state and local laws governing the use, handling, storage and
disposal of hazardous and biological materials because its
research
and development involve the handling of potentially harmful
biological and hazardous materials.  If material, quantify the
expenses incurred relating to compliance with these laws.

Clinical and Scientific Advisory Boards - Page 66
28. Disclose whether members of these boards are also shareholders
and/or receive compensation as consultants.  If so, disclose the
amount of shares held and/or compensation paid.
2005 Equity Incentive Plan - Page 76
29. Update to disclose whether the company`s stockholders have
approved the 2005 equity incentive and employee stock purchase
plans.

Related Party Transactions - Page 81
30. Please provide the disclosure required by Item 404(d) of
Regulation S-K.
31. In order to give shareholders a complete picture of your
current
equity structure, please expand to discuss the issuance of
outstanding equity, including other classes of preferred stock,
including the identity of the holders and the purchase price.

Principal Stockholders - Page 82
32. For each entity, identify the individuals who have or share
voting and/or investment power over the securities held by the
entity.  See Rule 13d-3 for the definition of beneficial
ownership.

NASDAQ National Market Listing - Page 88
33. Update the status of your application for listing on the
NASDAQ
National Market.

Shares Eligible for Future Sale - Page 89

	Lock-Up Agreements - Page 89
34. If material, identify the securityholders that are not subject
to
lock-up agreements.

	Rule 144 - Page 89
35. Please quantify the number of restricted shares held by non-
affiliates that will be eligible for sale under Rule 144(k) after
the
expiration of the lock-up period and the number of restricted
shares
held by affiliates that will be subject to the volume and other
restrictions of Rule 144 after that date.

Financial Statements

Report of Independent Registered Public Accounting Firm - Page F-1
36. It appears that the middle paragraph to the audit report has
been
amended to include some of the suggested language from AU Section
9508.18.  The suggested modification from AU 9508.18 also includes
the following language "The Company is not required to have, nor
were
we engaged to perform, an audit of its internal control over
financial reporting."  Either revise to include this additional
sentence or have your auditors tell us why they believe revision
is
not necessary.
Consolidated Balance Sheets - Page F-2
37. Tell us why the item "accounts payable and accrued
liabilities"
should not be further disaggregated pursuant to Rule 5-02.20 to
Regulation S-X.

Note 6 - Redeemable Convertible Preferred Stock and Stockholders`
Equity (deficit) - Page F-14
38. We received and are considering the supplemental information
submitted on February 22, 2005.  From that submission we see that
the
preliminary range discussed with underwriters is between $5 and $7
per share. You indicate that the preliminary range is contingent
on
several factors specific to your proposed products including (1)
successful completion of certain clinical trials, (2) filing of a
premarket approval application for the short-term monitoring
product
and (3) successful implantations of the long-term product in new
patients.  Tell us when you expect to complete each of these
items.
Since the proposed range apparently assumed successful completion
of
these matters, supplementally clarify the expected timing of this
offering.  Please note that with respect to employee stock options
granted shortly before an initial public offering, we generally
believe that there should not be a significant difference between
the
common stock fair value used for APB 25 and the expected initial
offering price. We may have further comment.

Exhibit Index
39. We note your intention to file a number of exhibits by
amendment.
Please note that we may have additional comments after we have an
opportunity to review them.  Please confirm that you are filing
all
material agreements, including those with your suppliers and
licensees.
40. Please include an updated and signed consent from your
independent auditors with any amendment.

Part II

Item 15.  Recent Sales of Unregistered Securities - Page II-2
41. Revise to name the persons or identify the class of persons to
whom the Series C and D redeemable convertible preferred stock
were
sold.  The disclosure that these shares were sold to "private
investors" is not descriptive.

      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.

	Notwithstanding our comments, in the event the company
requests
acceleration of the effective date of the pending registration
statement, it should fur