Margretta Diemer, M.D.
Internal Medicine Physician · Bethesda, MD
Margretta Diemer, M.D. is an internal medicine physician with a practice address in Bethesda, Maryland, and NPI 1669543252, issued on Nov 13, 2006. Check the license on the Maryland Board of Physicians; the Medicare figures below come from public CMS files.
- Name
- Margretta Diemer
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 0101034873 VA
Self-reported in NPPES; status is on the state search - Practice location
- Wrnmmc, Pcmh, Bldg 19, Bethesda, MD 20889
- Phone
- (301) 319-4326
- Enumerated
- Nov 13, 2006
- Record last updated
- Nov 16, 2023
- Fax
- (301) 400-0618
- Medicare enrollment
- Enrolled (PECOS I20110120001107); accepts Medicare assignment
- Medical or professional school
- Georgetown University School Of Medicine, 1979
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 3,904 in Maryland → Look up another NPI →
Verify Margretta Diemer in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMaryland Board of PhysiciansCheck the board
- 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Bills Medicare through one group practice
- Suburban/nrh Medical Rehabilitation IncBethesda, MD
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Margretta Diemer among 3,904 internal medicine physician records in Maryland
Margretta Diemer, M.D. is one of 3,904 internal medicine physician records with a practice address in Maryland. 77% 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 9% of them.
- NPI issued2006 · 9% of these records are older, 55% newer
- In a Medicare fileYes · 77% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1979 · median 2003 among the 2,445 with a school on file
- Record last updated2023 · 59% 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 Maryland practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
288 internal medicine physician records list a practice address in Bethesda
They are 288 of the 7,245 NPPES records with a practice address in Bethesda, and 3,904 internal medicine physician records in Maryland.
All 3,904 in Maryland → Every provider in Bethesda → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Darrell Baranko, M.D.Bethesda, MD 208891366431082
- Jeffrey Blair, M.D.Bethesda, MD 208891184625378
- Richard Catherina, M.D.Bethesda, MD 208891437131505
- Kim Gibson, MDBethesda, MD 208891700861374
- Heather Grote, MDBethesda, MD 208891275512204
- Paul Han, MDBethesda, MD 208891144205162
- Douglas Hawk, M.D.Bethesda, MD 208891013990886
- Christopher Martin, M.D.Bethesda, MD 208891750362505
Common questions
What is Margretta Diemer, M.D.'s NPI number?
Margretta Diemer, M.D.'s National Provider Identifier (NPI) is 1669543252, issued on Nov 13, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Margretta Diemer, M.D. located?
The NPPES record lists a practice address at Wrnmmc, Pcmh, Bldg 19, Bethesda, MD, 20889. Phone: (301) 319-4326. Providers update this record themselves, so call before visiting.
How can I verify Margretta Diemer, M.D.'s license?
Search the Maryland Board of Physicians at https://www.mbp.state.md.us/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
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.