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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. *)
DEXCOM INC
(Name of Issuer)
COMMON STOCK
(Title of Class of Securities)
252131107
(CUSIP Number)
DECEMBER 31, 2006
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:
[_X_] Rule 13d-1(b)
[___] Rule 13d-1(c)
[___] Rule 13d-1(d)
* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.
The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).
Potential persons who are to respond to the collection of information contained
in this form are not required to respond unless the form displays a currently
valid OMB control number.
SEC 1745 (3-98) Page 1 of 4 pages
Page 1
CUSIP No. Page 2 of 4 Pages
252131107
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
FRONTIER CAPITAL MANAGEMENT CO., LLC.
--------------------------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a) [ ]
(b) [ ]
--------------------------------------------------------------------------------
3 SEC USE ONLY
--------------------------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
DELAWARE
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NUMBER OF 5 SOLE VOTING POWER 1,601,800
SHARES
BENEFICIALLY ----------------------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH
REPORTING ----------------------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER 1,601,800
WITH
----------------------------------------------------
8 SHARED DISPOSITIVE POWER
--------------------------------------------------------------------------------
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,601,800
--------------------------------------------------------------------------------
10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
(See Instructions)
--------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
5.700%
--------------------------------------------------------------------------------
12 TYPE OF REPORTING PERSON (See Instructions)
IA
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Page 2
CUSIP No. 13G Page 3 of 4 Pages
252131107
ITEM 1.
(a) Name of Issuer:
DEXCOM INC
(b) Address of Issuer's Principal Executive Offices:
5555 OBERLIN DRIVE
SAN DIEGO, CA 92121
ITEM 2.
(a) Name of Person Filing:
FRONTIER CAPITAL MANAGEMENT LLC.
(b) Address of Principal Business Office:
99 SUMMER STREET, BOSTON, MA 02110
(c) Citizenship:
DELAWARE
(d) Title of Class of Securities:
COMMON STOCKS
(e) CUSIP Number:
252131107
ITEM 3. If this statement is filed pursuant to rule 240.13d-1(b) or
240.13d-2(b) or (c), check whether the person filing is a:
(a) [ ] Broker or dealer registered under section 15 of the Act (15
U.S.C. 78o).
(b) [ ] Bank as defined in section 3(a)(6) of the Act
(15 U.S.C. 78c).
(c) [ ] Insurance company as defined in section 3(a)(19) of the Act
(15 U.S.C. 78c).
(d) [ ] Investment company registered under section 8 of the
Investment Company Act of 1940 (15 U.S.C. 80a-8).
(e) [X] An investment adviser in accordance with
240.13d-1(b)(1)(ii)(E).
(f) [ ] An employee benefit plan or endowment fund in accordance
with 240.13d-1(b)(1)(ii)(F).
(g) [ ] A parent holding company or control person in accordance
with 240.13d-1(b)(1)(ii)(G)
(h) [ ] A savings association as defined in section 3(b) of the
Federal Deposit Insurance Act (12 U.S.C. 1813).
(i) [ ] A church plan that is excluded from the definition of an
investment company under section 3(c)(14) of the Investment
Company Act of 1940 (15 U.S.C. 80a-3).
(j) [ ] Group, in accordance with section 240.13d-1(b)(1)(ii)(J)
Page 3
CUSIP No. 13G Page 4 of 4 Pages
252131107
ITEM 4. OWNERSHIP
(a) Amount Beneficially Owned:
1,601,800
(b) Percent of Class:
5.700%
(c) Number of Shares as to which such person has:
1,601,800
ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
If this statement is being filed to report the fact that as of the date hereof
the reporting person has ceased to be the beneficial owner of more than five
percent of the class of securities, check the following [___].
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH
ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
ITEM 9. NOTICE OF DISSOLUTION OF GROUP
ITEM 10. CERTIFICATION
By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were not acquired and are not held for the purpose
of or with the effect of changing or influencing the control of the issuer of
the securities and were not acquired and are not held in connection with or as a
participant in any transaction having that purpose or effect.
DATED: By: /s/ William J. Ballou
JANUARY 2, 2007 ------------------------------------
Name: William J. Ballou
Title: CHIEF OPERATING OFFICER
Page 4