Aaron Barak Neinstein, MD
Endocrinology, Diabetes & Metabolism Physician · San Francisco, CA
Aaron Barak Neinstein, MD is an endocrinology, diabetes & metabolism physician with a practice address in San Francisco, California, and NPI 1205074028, issued on Feb 2, 2009. Check the license (California A106501, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Aaron Barak Neinstein
- Credential
- MD
- Primary taxonomy
- Endocrinology, Diabetes & Metabolism Physician 207RE0101X
- License number
- A106501 CA
Self-reported in NPPES; status is on the state search - Practice location
- 400 Parnassus Avenue, San Francisco, CA 94143
- Phone
- (415) 353-2350
- Enumerated
- Feb 2, 2009
- Record last updated
- May 15, 2018 (not updated in 8 years: call before relying on the address or phone)
- Fax
- (415) 353-2337
- Medicare enrollment
- Enrolled (PECOS I20100724000027); accepts Medicare assignment
- Medical or professional school
- University Of Southern California Keck School Of Medicine, 2007
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest endocrinology, diabetes & metabolism physician records → All 1,131 in California → Look up another NPI →
Also registered at 400 Parnassus Avenue
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Christi ButlerUrology Physician1043639321
- Marc Kristensen, DPTPhysical Therapist1386993822
- Udaybir Mann, M.D.Student in an Organized Health Care Education/Training Program1699516856
- Marko Petrovic, M.D.Neuromusculoskeletal Medicine & OMM Physician1437343183
- Mary Potts, PTPhysical Therapist1457601452
- Nina Shah, M.D.Internal Medicine Physician1063692614
Verify Aaron Barak Neinstein in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A106501Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
97% fewer Medicare Part D claims than the average endocrinology, diabetes & metabolism physician in 2024
80 Medicare Part D claims for 19 beneficiaries, against an average of 2,630 among the 8,223 providers of this specialty who prescribed in Part D. Brand-name drugs were 61% of claims.
Most prescribed
- Ozempic20 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 one group practice
- Regents OF The University OF CaliforniaSan Francisco, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Aaron Barak Neinstein among 1,131 endocrinology, diabetes & metabolism physician records in California
Aaron Barak Neinstein, MD is one of 1,131 endocrinology, diabetes & metabolism physician records with a practice address in California. 84% 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 64% of them.
- NPI issued2009 · 64% of these records are older, 32% newer
- In a Medicare fileYes · 84% of these records are
- In the CMS Doctors and Clinicians fileYes · 69% of these records are
- Graduated2007 · median 2003 among the 779 with a school on file
- Record last updated2018 · 57% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RE0101X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Endocrinology, Diabetes & Metabolism Physician providers in California
There are 1,131 endocrinology, diabetes & metabolism physician records in California.
All 1,131 in California → Every provider in San Francisco → Endocrinology, Diabetes & Metabolism Physician nationwide →
The 8 endocrinology, diabetes & metabolism physician records with the nearest ZIP codes
- Mark Anderson, MDSan Francisco, CA 941431013971001
- Lewis Blevins, MDSan Francisco, CA 941431295822393
- Merl Charles, MD PHDSan Francisco, CA 941431023152055
- Ira Goldfine, MDSan Francisco, CA 941431508823675
- Eric Goldman, M.D.San Francisco, CA 941431922194869
- Elizabeth Holt, MDSan Francisco, CA 941431184607392
- Victoria Hsiao, MD, PHDSan Francisco, CA 941431659418655
- Martha Kennedy, M.D.San Francisco, CA 941431982651022
Common questions
What is Aaron Barak Neinstein, MD's NPI number?
Aaron Barak Neinstein, MD's National Provider Identifier (NPI) is 1205074028, issued on Feb 2, 2009. An NPI identifies a provider in billing; it is not a license.
Where is Aaron Barak Neinstein, MD located?
The NPPES record lists a practice address at 400 Parnassus Avenue, San Francisco, CA, 94143. Phone: (415) 353-2350. Providers update this record themselves, so call before visiting.
How can I verify Aaron Barak Neinstein, MD's license?
NPPES lists California license number A106501, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Aaron Barak Neinstein, MD prescribe under Medicare Part D?
In 2024, Aaron Barak Neinstein, MD had 80 Medicare Part D claims for 19 beneficiaries; the average among endocrinology, diabetes & metabolism physician prescribers was 2,630. 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.