Eric John Dieffenbach, M.D.
Psychiatry Physician · New Canaan, CT
Eric John Dieffenbach, M.D. is a psychiatry physician with a practice address in New Canaan, Connecticut, and NPI 1497082614, issued on Nov 9, 2009. Check the license (Connecticut 032401, as entered in NPPES) on the Connecticut Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Eric John Dieffenbach
- Credential
- M.D.
- Primary taxonomy
- Psychiatry Physician 2084P0800X
- License number
- 032401 CT
Self-reported in NPPES; status is on the state search - Practice location
- 72 Park St, New Canaan, CT 06840
- Phone
- (203) 858-1275
- Enumerated
- Nov 9, 2009
- Record last updated
- Nov 9, 2009 (not updated in 17 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest psychiatry physician records → All 1,174 in Connecticut → Look up another NPI →
Also registered at 72 Park St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Eric John Dieffenbach in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersConnecticut Medical Examining Board
Search for license 032401Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
91% fewer Medicare Part D claims than the average psychiatry physician in 2024
86 Medicare Part D claims, against an average of 1,000 among the 35,054 providers of this specialty who prescribed in Part D. Brand-name drugs were 0% of claims.
Most prescribed
- Clonazepam14 claims
- Fluoxetine Hcl14 claims
- Lamotrigine12 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.
Eric John Dieffenbach among 1,174 psychiatry physician records in Connecticut
Eric John Dieffenbach, M.D. is one of 1,174 psychiatry physician records with a practice address in Connecticut. 70% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2009, is newer than 61% of them.
- NPI issued2009 · 61% of these records are older, 37% newer
- In a Medicare fileYes · 70% of these records are
- In the CMS Doctors and Clinicians fileNo · 43% of these records are
- Record last updated2009 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2084P0800X and a Connecticut practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
15 psychiatry physician records list a practice address in New Canaan
They are 15 of the 276 NPPES records with a practice address in New Canaan, and 1,174 psychiatry physician records in Connecticut.
All 1,174 in Connecticut → Every provider in New Canaan → Psychiatry Physician nationwide →
The 8 psychiatry physician records with the nearest ZIP codes
- Kenneth Berv, MDNew Canaan, CT 068401457456261
- Andre Burey, MDNew Canaan, CT 068401184019440
- Ryan Flanagan, MDNew Canaan, CT 068401750886701
- Laura Gardner, M.D.New Canaan, CT 068401912295932
- Irwin Gelman, M.D.New Canaan, CT 068401154447282
- Andrew Gerber, M.D., PH.D.New Canaan, CT 068401477686855
- Joseph Goldberg, MDNew Canaan, CT 068401194948323
- Marie Handler, M.D.New Canaan, CT 068401730342288
Common questions
What is Eric John Dieffenbach, M.D.'s NPI number?
Eric John Dieffenbach, M.D.'s National Provider Identifier (NPI) is 1497082614, issued on Nov 9, 2009. An NPI identifies a provider in billing; it is not a license.
Where is Eric John Dieffenbach, M.D. located?
The NPPES record lists a practice address at 72 Park St, New Canaan, CT, 06840. Phone: (203) 858-1275. Providers update this record themselves, so call before visiting.
How can I verify Eric John Dieffenbach, M.D.'s license?
NPPES lists Connecticut license number 032401, 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 Eric John Dieffenbach, M.D. prescribe under Medicare Part D?
In 2024, Eric John Dieffenbach, M.D. had 86 Medicare Part D claims; the average among psychiatry physician prescribers was 1,000. 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.