Darren S. O'Neill, M.D.
Internal Medicine Physician · Enfield, CT
Darren S. O'Neill, M.D. is an internal medicine physician with a practice address in Enfield, Connecticut, and NPI 1861434607, issued on Jun 12, 2006. Check the license (Connecticut 36429, as entered in NPPES) on the Connecticut Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Darren S. O'Neill
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License numbers
- 36429 CT
151285 MA
Self-reported in NPPES; status is on the state search - Practice location
- 701 Enfield St, Enfield, CT 06082
- Phone
- (860) 741-6058
- Enumerated
- Jun 12, 2006
- Record last updated
- May 19, 2026
- Fax
- (413) 733-5860
- Medicaid ID
- 3176835 MA
- Medicare enrollment
- Enrolled (PECOS I20100929001009); accepts Medicare assignment
- Medical or professional school
- University Of Connecticut School Of Medicine, 1994
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 2,623 in Connecticut → Look up another NPI →
Also registered at 701 Enfield St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- John Bedford, M.D.Internal Medicine Physician1912965542
- Cailyn Bolduc, PA-CMedical Physician Assistant1215748355
- Peter Drennan, D.O.Internal Medicine Physician1629043625
- Patrick Gibson, PA-C, MHPMedical Physician Assistant1861406597
- Izabela Krakowiak Colasacco, D.O.Internal Medicine Physician1972795102
- Karen Krustapentus, APRN, BCNurse Practitioner1285660860
Verify Darren S. O'Neill in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersConnecticut Medical Examining Board
Search for license 36429Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
6.0 times the Medicare Part D claims of the average internal medicine physician in 2024
18,970 Medicare Part D claims for 1,268 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 12% of claims. 628 claims were for opioids.
Most prescribed
- Atorvastatin Calcium1,198 claims
- Amlodipine Besylate785 claims
- Omeprazole723 claims
- Lisinopril703 claims
- Gabapentin477 claims
- Levothyroxine Sodium461 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through 2 group practices
- Baystate Medical Practices IncEnfield, CT
- Springfield Medical Associates, Inc.Enfield, CT
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Darren S. O'Neill among 2,623 internal medicine physician records in Connecticut
Darren S. O'Neill, M.D. is one of 2,623 internal medicine physician records with a practice address in Connecticut. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 11% of them.
- NPI issued2006 · 11% of these records are older, 52% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1994 · median 2004 among the 1,646 with a school on file
- Record last updated2026 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Connecticut practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
17 internal medicine physician records list a practice address in Enfield
They are 17 of the 989 NPPES records with a practice address in Enfield, and 2,623 internal medicine physician records in Connecticut.
All 2,623 in Connecticut → Every provider in Enfield → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- John Bedford, M.D.Enfield, CT 060821912965542
- Joseph Breton, M.DEnfield, CT 060821932206232
- Miriam Buckberg, MDEnfield, CT 060821578549010
- George Donahue, MDEnfield, CT 060821710964325
- Peter Drennan, D.O.Enfield, CT 060821629043625
- Marat Gitman, DOEnfield, CT 060821396907069
- Izabela Krakowiak Colasacco, D.O.Enfield, CT 060821972795102
- Francis Murray, M.D.Enfield, CT 060821528026499
Common questions
What is Darren S. O'Neill, M.D.'s NPI number?
Darren S. O'Neill, M.D.'s National Provider Identifier (NPI) is 1861434607, issued on Jun 12, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Darren S. O'Neill, M.D. located?
The NPPES record lists a practice address at 701 Enfield St, Enfield, CT, 06082. Phone: (860) 741-6058. Providers update this record themselves, so call before visiting.
How can I verify Darren S. O'Neill, M.D.'s license?
NPPES lists Connecticut license number 36429, as entered by the provider. Search the Connecticut Medical Examining Board at https://www.elicense.ct.gov/Lookup/LicenseLookup.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Darren S. O'Neill, M.D. prescribe under Medicare Part D?
In 2024, Darren S. O'Neill, M.D. had 18,970 Medicare Part D claims for 1,268 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.