<PAGE>
                                                                   Exhibit 10.20

                        FIRST LOAN MODIFICATION AGREEMENT

      This First Loan Modification Agreement (this "Agreement") is entered into
as of February 19, 2004, by and among ANIMAS CORPORATION, a Delaware
corporation ("Company"), whose address is 530 Lancaster Avenue, Frazer,
Pennsylvania 19355 and ANIMAS DIABETES CARE, LLC, a Delaware limited liability
company, whose address is 530 Lancaster Avenue, Frazer, Pennsylvania 19355
(together with the Company, each a "Borrower" and collectively, the
"Borrowers"), and SILICON VALLEY BANK ("Lender") whose address is 3003 Tasman
Drive, Santa Clara, California 95054 and with a loan production office located
at 5 Radnor Corp. Center, 100 Matsonford Drive, Suite 555, Radnor, Pennsylvania
19087.

1.    DESCRIPTION OF EXISTING INDEBTEDNESS: Among other indebtedness which may
be owed by Borrowers to Lender, Borrowers are indebted to Lender pursuant to,
among other documents, a Loan and Security Agreement dated as of November 7,
2003 between Borrowers and Lender (as may be amended from time to time, the
"Loan Agreement"). Hereinafter, all indebtedness owed by Borrowers to Lender
pursuant to the Loan Agreement shall be referred to as the "Indebtedness."

2.    DESCRIPTION OF COLLATERAL. Repayment of the Indebtedness is secured by the
Collateral as described in the Loan Agreement. Hereinafter, the above-described
Loan Agreement, together with all other documents securing repayment of the
Indebtedness shall be referred to as the "Security Documents". Hereinafter, the
Security Documents, together with all other documents evidencing or securing the
Indebtedness shall be referred to as the "Existing Loan Documents".

3.    DESCRIPTION OF CHANGE IN TERMS.

      A.    Modification to Loan Agreement. The Tangible Net Worth covenant set
            forth in that certain Schedule to Loan and Security Agreement dated
            as of November 7, 2003 by and among the parties hereto is hereby
            deleted in its entirety and replaced with the following:

                  Minimum Tangible Net Worth:

                  Borrower shall maintain a Tangible Net Worth as of the last
                  day of each month of not less than the sum of (a) and (b):

<TABLE>
<CAPTION>
                  (a)   Tangible Net Worth:     Applicable Period:
                        ------------------      -----------------
<S>                     <C>                     <C>
                        $7,000,000              from November 7, 2003 through December 31, 2003;
                        $5,500,000              January 31, 2004 through May 31, 2004;
                        $6,000,000              June 30, 2004 through August 31, 2004; and
                        $7,500,000              September 30, 2004 and thereafter;
</TABLE>

                  plus

                  (b)   fifty percent (50%) of the net proceeds from any
                        issuance by Borrower of equity or subordinated debt
                        after November 7, 2003.

                  DEFINITIONS.      For purposes of the foregoing financial
                                    covenants, the following term shall have the
                                    following meaning:
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                                    "Tangible Net Worth" shall mean the excess
                                    of total assets over total liabilities,
                                    determined in accordance with GAAP, with the
                                    following adjustments:

                                          (A) there shall be excluded from
                                    assets: (i) notes, accounts receivable and
                                    other obligations owing to Borrower from its
                                    officers or other Affiliates, (ii) all
                                    assets which would be classified as
                                    intangible assets under GAAP, including
                                    without limitation goodwill, licenses,
                                    patents, trademarks, trade names,
                                    copyrights, capitalized software and
                                    organizational costs, licenses and
                                    franchises, and (iii) all accrued dividends.

                                          (B) there shall be excluded from
                                    liabilities: (i) all indebtedness which is
                                    subordinated to the Obligations under a
                                    subordination agreement in form specified by
                                    Silicon or by language in the instrument
                                    evidencing the indebtedness which Silicon
                                    agrees in writing is acceptable to Silicon
                                    in its good faith business judgment and (ii)
                                    all of Borrower's revenue which is deferred
                                    pursuant to Securities and Exchange
                                    Commission Release No. SAB 104.

4.    WAIVER OF DEFAULT. Borrowers failed to comply with the Tangible Net Worth
covenant for the months ending November 30, 2003 and December 31, 2003 due to
the deferral of revenue per SAB 104, and Lender hereby waives such Events of
Default to the extent that they were caused by the deferral of revenue per SAB
104.

5.    PAYMENT OF VARIANCE FEE. In consideration of Lender's entering into this
Agreement and that certain Second Loan Modification Agreement dated of even date
herewith by and among the parties hereto in connection with other indebtedness
owed by Borrower to Lender, Borrowers shall pay to Lender a non refundable
variance fee in the aggregate amount of Two Thousand Five Hundred Dollars
($2,500) plus all out-of-pocket expenses (including, but not limited to fees and
expenses of Lender's counsel).

6.    CONSISTENT CHANGES. The Existing Loan Documents are hereby amended
wherever necessary to reflect the changes described above.

7.    NO DEFENSES OF BORROWERS. Borrowers hereby waive any and all defenses
against the payment of the Indebtedness or performance of any obligations under
the Existing Loan Documents, which they have as of the date hereof, whether
known or unknown, contingent or non-contingent. This waiver is knowingly given
after consultation with counsel of Borrowers' own choosing.

8.    CONTINUING VALIDITY. Borrowers understand and agree that in modifying the
existing Indebtedness, Lender is relying upon Borrowers' representations,
warranties, and agreements, as set forth in the Existing Loan Documents. Except
as expressly modified pursuant to this Agreement, the terms of the Existing Loan
Documents remain unchanged and in full force and effect. Lender's agreement to
modifications to the existing Indebtedness pursuant to this Agreement in no way
shall obligate Lender to make any future modifications to the Indebtedness.
Nothing in this Agreement shall constitute a satisfaction of the Indebtedness.
It is the intention of Lender and Borrowers to retain as liable parties all
makers and endorsers of the Existing Loan Documents, unless the party is
expressly released by Lender in writing. No maker, endorser, or guarantor will
be released by virtue of this Agreement. The terms of this paragraph apply not
only to this Agreement, but also to all subsequent loan modification agreements
except to the extent expressly changed or terminated by the terms thereof.

                         [Signatures on Following Page]


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<PAGE>
      This First Loan Modification Agreement is executed as of the date first
written above.

BORROWERS:                                      LENDER:

ANIMAS CORPORATION                              SILICON VALLEY BANK

By: /s/ Richard A. Baron                        By: /s/ David Rodriguez
   ---------------------------                     ---------------------------
Name: Richard A. Baron                          Name: David Rodriguez
     -------------------------                       -------------------------
Title: CFO                                      Title: VP
      ------------------------                        ------------------------

ANIMAS DIABETES CARE, LLC

BY:   ANIMAS CORPORATION, ITS SOLE MEMBER

      By:    /s/ Richard A. Baron
             ------------------------
             Name: Richard A. Baron
             Title: CFO


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