Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Gustavo A. Diaz, MD

Emergency Medicine Physician in Redwood City, CA · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1538122635

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Registry record

Entity type Individual (Type 1)

Name Gustavo A. Diaz

Credential MD

Sex Male

Practice address 830 Jefferson Ave, Redwood City, CA, 94063

Phone (650) 381-0616

Enumeration date Apr 10, 2006

Last updated in NPPES Mar 16, 2026

Taxonomy & licenses

207P00000X Emergency Medicine Physician Allopathic & Osteopathic Physicians · License C54872 (CA) Primary

207P00000X Emergency Medicine Physician Allopathic & Osteopathic Physicians · License 53006 (MA) Secondary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
000000006706	Other	MA	BMC
04-3329195	Other	MA	NORTH AMERICAN PREFERRED
04-3329195	Other	MA	GREAT-WEST
102531	Other	MA	CIGNA
2359897	Other	MA	AETNA
04-3329195	Other	MA	PHCS
04-3329195	Other	MA	UNICARE/GIC
04-3329195	Other	MA	NORTHEAST HEALTHCARE ALLI
04-3329195	Other	MA	NORTHEAST HEALTH DIRECT
04-3329195	Other	MA	PLAN VISTA
053006	Other	MA	TUFTS
24922	Other	MA	HEALTH NEW ENGLAND
3000915	Medicaid	MA	-
438822	Other	MA	HARVARD PILGRIM
632919	Other	MA	CONNECTICARE
J08576	Other	MA	BCBS MA
04-3329195	Other	MA	CONSOLIDATED

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is Gustavo Diaz?

Gustavo Diaz is registered in NPPES with the primary taxonomy of Emergency Medicine Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Other providers at this practice address

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Raphael Vassor Physician Assistant · Redwood City, CA NPI 1174552970 James Simmons Family Nurse Practitioner · Redwood City, CA NPI 1366744492

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2026-03-16.