Karthik Gunachelvan
Internal Medicine Physician · Darien, CT
Karthik Gunachelvan is an internal medicine physician with a practice address in Darien, Connecticut, and NPI 1740604941, issued on Feb 7, 2014. Check the license (Connecticut 82825, as entered in NPPES) on the Connecticut Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Karthik Gunachelvan
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 82825 CT
Self-reported in NPPES; status is on the state search - Practice location
- 1500 Post RD Ste 100, Darien, CT 06820
- Phone
- (203) 655-8749
- Enumerated
- Feb 7, 2014
- Record last updated
- Oct 21, 2025
- Fax
- (203) 656-0701
- Medicare enrollment
- Enrolled (PECOS I20251125002150); accepts Medicare assignment
- 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 1500 Post RD Ste 100
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Margaret BaranInternal Medicine Physician1285623843
Verify Karthik Gunachelvan in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersConnecticut Medical Examining Board
Search for license 82825Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.6 times the Medicare Part D claims of the average internal medicine physician in 2024
8,148 Medicare Part D claims for 914 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 13% of claims. 340 claims were for opioids.
Most prescribed
- Atorvastatin Calcium678 claims
- Amlodipine Besylate513 claims
- Lisinopril371 claims
- Omeprazole280 claims
- Gabapentin272 claims
- Levothyroxine Sodium258 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 3 group practices
- Riverbend Medical Group IncSpringfield, MA
- Select Rehabilitation, LLCGlenview, IL
- Stamford Health Medical Group IncDarien, CT
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Karthik Gunachelvan among 2,623 internal medicine physician records in Connecticut
Karthik Gunachelvan 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 2014, is newer than 72% of them.
- NPI issued2014 · 72% of these records are older, 26% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2013 · median 2004 among the 1,646 with a school on file
- Record last updated2025 · 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).
15 internal medicine physician records list a practice address in Darien
They are 15 of the 380 NPPES records with a practice address in Darien, and 2,623 internal medicine physician records in Connecticut.
All 2,623 in Connecticut → Every provider in Darien → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Gene Balboa, MDDarien, CT 068201841366820
- Margaret BaranDarien, CT 068201285623843
- Susan Collins, M.D.Darien, CT 068201306877626
- Amanda Collins- Baine, M.D.Darien, CT 068201154340040
- Mark Dam, M.DDarien, CT 068201720005507
- James Dorr, M.D.Darien, CT 068201427367705
- William Giesen, M.D.Darien, CT 068201124104724
- Carolyn Langelier, M.D.Darien, CT 068201780930933
Common questions
What is Karthik Gunachelvan's NPI number?
Karthik Gunachelvan's National Provider Identifier (NPI) is 1740604941, issued on Feb 7, 2014. An NPI identifies a provider in billing; it is not a license.
Where is Karthik Gunachelvan located?
The NPPES record lists a practice address at 1500 Post RD Ste 100, Darien, CT, 06820. Phone: (203) 655-8749. Providers update this record themselves, so call before visiting.
How can I verify Karthik Gunachelvan's license?
NPPES lists Connecticut license number 82825, 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 Karthik Gunachelvan prescribe under Medicare Part D?
In 2024, Karthik Gunachelvan had 8,148 Medicare Part D claims for 914 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.