SecProbe.io

October 15 , 2013
Via E -mail
Kim D. Blickenstaff
President and Chief Executive Officer
Tandem Diabetes Care, Inc.
11045 Roselle Street
San Diego, CA  92121

Re: Tandem Diabetes Care, Inc.
Registration Statement on Form S-1
Filed  October  7, 2013
  File No. 333 -191601

Dear Mr. Blickenstaff :

We have reviewed your registration statement  and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.

Please respond to this letter by amending your registration statement and providing the
requested information.   Where you do not believe our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.

After reviewing any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.

Artwork

1. We refer to prior comment 1 and your revisions on the second page of graphics.  We note
that the text above the display monitor explains to investors that the center graphic is
your “t:slim Insulin Pump.”  Accordingly, the icons and accompanying text do not appear
necessary to explain your visuals.  Additionally, it is not appropriate to  highlight “key
product features” in your artwork without balancing the presentation to highlight key
product limitations and/or competitive disadvantages.   Please revise your graphics
accordingly.

The Market, page 2

2. We note your response to prior comment 10; however, the report does not clarify how the
5% estimate was calculated or whether any assumptions were necessary to derive the
figure.  Please provide us with this information .  To the extent assumptions were used,
please revise your disclosur e where you cite the figure to provide the necessary context.

Kim D. Blickenstaff
Tandem Diabetes Care, Inc.
October 15 , 2013
Page 2

 For instance, if the estimate does not reflect any patients who return to injections or
otherwise stop using a pump, revise to so state.

Sales and Marketing, page 76

3. We note your revised di sclosure identifying your 10% customers and refer to Schedule
7.14 to Exhibit 10.2, which indicates that you have distribution agreements with both
10% customers.  Please file these agreements as material contracts or explain why you
believe they are not m aterial.

Manufacturing and Quality Assurance, page 79

4. With a view to disclosure concerning your manufacturing, please tell us about the nature
of the OEM Agreement and the Manufacturing Agreement which are referenced in items
6 and 33 in Schedule 7.14 to  Exhibit 10.2.

Intellectual Property, page 81

5. We note your response to prior comment 33 .  Given the size of the license fee payment
relative to your revenues and  your operating and net losses , it is not clear how you
determined that the agreement is not required to be disclosed and filed as an exhibit t o
your registration statement.  Please revise to disclose the identity of the unnamed party
and file the agreement.

Market Comparisons, page 99

6. We note your response to prior comment 36; however, to the extent that you benchmark
total compensation to that of the companies contained in the surveys you or your
consultants used, please revise your disclosure to identify the surveys used and their
components,  including component companies.  Refer to Item 402( b)(2)(xiv) of
Regulation S -K.

We urge al l persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Act of 1933 and
all applicable Securities Act rules require.   Since the company and its manage ment 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 you request acceleration of the effective date
of the pending registration statement please provide a written statement from the company
acknowledging that:

 should the Commission or the staff, acting pursuant to delegated authority, declare the
filing effective, it does not foreclose the Commission from ta king any action with respect
to the filing;

Kim D. Blickenstaff
Tandem Diabetes Care, Inc.
October 15 , 2013
Page 3

 the action of the Commission or the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not relieve the company from its full responsibility for
the adequacy and accuracy of t he disclosure in the filing; and

 the company may not assert staff comments and the declaration of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the federal
securities laws of the United States.

Please refer to Rules 460 and 461 regarding requests for acceleration.  We will consider a
written request for acceleration of the effective date of the registration statement as confirmation
of the fact that those requesting acceleration are aware of thei r respective responsibilities under
the Securities Act of 1933 and the Securities Exchange Act of 1934 as they relate to the proposed
public offering of the securities specified in the above registration statement.  Please allow
adequate time for us to rev iew any amendment prior to the requested effective date of the
registration statement.

You may contact Jeanne Bennett  at (202) 551-3606  or Brian Cascio, Accounting Branch
Chief,  at (202) 551-3676  if you have questions regarding comments on the financial statements
and related matters.  Please contact Joseph McCann  at (202) 551-6262 or Mary Beth Breslin ,
Senior Attorney, at (202) 551-3625  with any other questions.

Sincerely,

 /s/ Mary Beth Bresl in for

 Amanda Ravitz
Assistant Director

cc (via email):  Ryan C. Wilkins , Esq.  – Stradling Yocca Carlson & Rauth, P.C.