Gustavo A. Diaz, MD
Emergency Medicine Physician · Redwood City, CA
Gustavo A. Diaz, MD is an emergency medicine physician with a practice address in Redwood City, California, and NPI 1538122635, issued on Apr 10, 2006. Check the license (California C54872, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Gustavo A. Diaz
- Credential
- MD
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License numbers
- C54872 CA
53006 MA
Self-reported in NPPES; status is on the state search - Practice location
- 830 Jefferson Ave, Redwood City, CA 94063
- Phone
- (650) 381-0616
- Enumerated
- Apr 10, 2006
- Record last updated
- Mar 16, 2026
- Medicaid ID
- 3000915 MA
- Medicare enrollment
- Enrolled (PECOS I20111213000435); accepts Medicare assignment
- Medical or professional school
- University Of Texas Medical Branch At Galveston, 1982
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 830 Jefferson Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- James Simmons, NPFamily Nurse Practitioner1366744492
- Raphael Vassor, P.A.Physician Assistant1174552970
Verify Gustavo A. Diaz in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license C54872Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
86% fewer Medicare Part D claims than the average emergency medicine physician in 2024
31 Medicare Part D claims for 16 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. Brand-name drugs were 0% of 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
- American Current Care OF California A Medical CorporationGilroy, CA
- Doctors ON Duty Medical Group, IncSanta Cruz, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Gustavo A. Diaz among 7,751 emergency medicine physician records in California
Gustavo A. Diaz, MD is one of 7,751 emergency medicine physician records with a practice address in California. 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 4% of them.
- NPI issued2006 · 4% of these records are older, 60% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 59% of these records are
- Graduated1982 · median 2011 among the 4,560 with a school on file
- Record last updated2026 · 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 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Emergency Medicine Physician providers in California
There are 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Redwood City → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- James Ahn, MDRedwood City, CA 940631528146180
- Sunil Bhopale, MDRedwood City, CA 940631760561807
- George Bulloch, MDRedwood City, CA 940631134207723
- Walter Eades, MDRedwood City, CA 940631467530006
- Micheal Heinrich, M.D.Redwood City, CA 940631427150531
- Adam Landsdorf, MDRedwood City, CA 940631134207798
- Gregg Letsinger, MDRedwood City, CA 940631962580555
- John Rosenberg, MDRedwood City, CA 940631558449199
Common questions
What is Gustavo A. Diaz, MD's NPI number?
Gustavo A. Diaz, MD's National Provider Identifier (NPI) is 1538122635, issued on Apr 10, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Gustavo A. Diaz, MD located?
The NPPES record lists a practice address at 830 Jefferson Ave, Redwood City, CA, 94063. Phone: (650) 381-0616. Providers update this record themselves, so call before visiting.
How can I verify Gustavo A. Diaz, MD's license?
NPPES lists California license number C54872, 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 Gustavo A. Diaz, MD prescribe under Medicare Part D?
In 2024, Gustavo A. Diaz, MD had 31 Medicare Part D claims for 16 beneficiaries; the average among emergency medicine physician prescribers was 226. 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.