NPPES file of Aug 9, 2026

Mark T. Shimazaki, DO

Geriatric Medicine (Internal Medicine) Physician · Santa Clara, CA

Mark T. Shimazaki, DO is a geriatric medicine (internal medicine) physician with a practice address in Santa Clara, California, and NPI 1275611717, issued on Nov 1, 2006. Check the license (California 20A8584, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.

Record from CMS NPPES, file of Aug 9, 2026 · Medicare files 2024 · method · Verify with CMS →

NPPES recordNPPES file of Aug 9, 2026
1275611717
Name
Mark T. Shimazaki
Credential
DO
Primary taxonomy
Geriatric Medicine (Internal Medicine) Physician 207RG0300X
License number
20A8584 CA
Self-reported in NPPES; status is on the state search
Practice location
710 Lawrence Expy, Santa Clara, CA 95051
Phone
(408) 851-1000
Enumerated
Nov 1, 2006
Record last updated
Dec 9, 2021 (not updated in 5 years: call before relying on the address or phone)
Medicare enrollment
Enrolled (PECOS I20070608000598); accepts Medicare assignment
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). Enrollment, assignment, school and telehealth: CMS Doctors and Clinicians file, Aug 2026. A record is not a license: verify it with the state board.
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8 nearest geriatric medicine (internal medicine) physician records → All 532 in California → Look up another NPI →

Also registered at 710 Lawrence Expy

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Iype Abraham, M.D.Internal Medicine Physician1578737243
  2. Oren Abramson, MDPediatric Gastroenterology Physician1265511307
  3. Jamie Adiarte, PA-CPhysician Assistant1073824413
  4. Sarah Adut, PHDClinical Psychologist1609484831
  5. Najla Ahmadzia, M.D.Student in an Organized Health Care Education/Training Program1568692580
  6. Farhana Ahmed, MDHospitalist Physician1215110002

Verify Mark T. Shimazaki in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMedical Board of California
    Search for license 20A8584    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Open the California license search

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21% more Medicare Part D claims than the average geriatric medicine (internal medicine) physician in 2024

5,117 Medicare Part D claims for 433 beneficiaries, against an average of 4,246 among the 3,116 providers of this specialty who prescribed in Part D. Brand-name drugs were 11% of claims. 144 claims were for opioids.

  1. Mark Shimazaki5,117
  2. Specialty average4,246

Most prescribed

  1. Atorvastatin Calcium422 claims
  2. Amlodipine Besylate265 claims
  3. Losartan Potassium197 claims
  4. Levothyroxine Sodium192 claims
  5. Tamsulosin Hcl152 claims
  6. Lisinopril150 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

  1. Permanente Medical Group IncSanta Clara, CA

Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).

Mark T. Shimazaki among 532 geriatric medicine (internal medicine) physician records in California

Mark T. Shimazaki, DO is one of 532 geriatric medicine (internal medicine) physician records with a practice address in California. 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 7% of them.

  • NPI issued2006 · 7% of these records are older, 46% newer
  • In a Medicare fileYes · 77% of these records are
  • In the CMS Doctors and Clinicians fileYes · 51% of these records are
  • Graduated2002 · median 1999 among the 271 with a school on file
  • Record last updated2021 · 62% of these records were not updated in five years or more

Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RG0300X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).

Geriatric Medicine (Internal Medicine) Physician providers in California

There are 532 geriatric medicine (internal medicine) physician records in California.

All 532 in California → Every provider in Santa Clara → Geriatric Medicine (Internal Medicine) Physician nationwide →

The 8 geriatric medicine (internal medicine) physician records with the nearest ZIP codes

  1. Myo Aung, MDSanta Clara, CA 950511588741441
  2. Marci Teresi, MDSanta Clara, CA 950511316024243
  3. Kathleen Kehmna, NPSanta Cruz, CA 950601740144047
  4. Robert Keet, M.D.Santa Cruz, CA 950651639272750
  5. Lawrence Rosenbaum, M.D.Santa Cruz, CA 950651467555474
  6. Linda Lu, M.D.Los Gatos, CA 950321659546596
  7. Bindu Chopra, M.D.Cupertino, CA 950141972587426
  8. Alice Lively Hamill, DOCupertino, CA 950141336228469

Common questions

What is Mark T. Shimazaki, DO's NPI number?

Mark T. Shimazaki, DO's National Provider Identifier (NPI) is 1275611717, issued on Nov 1, 2006. An NPI identifies a provider in billing; it is not a license.

Where is Mark T. Shimazaki, DO located?

The NPPES record lists a practice address at 710 Lawrence Expy, Santa Clara, CA, 95051. Phone: (408) 851-1000. Providers update this record themselves, so call before visiting.

How can I verify Mark T. Shimazaki, DO's license?

NPPES lists California license number 20A8584, 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 Mark T. Shimazaki, DO prescribe under Medicare Part D?

In 2024, Mark T. Shimazaki, DO had 5,117 Medicare Part D claims for 433 beneficiaries; the average among geriatric medicine (internal medicine) physician prescribers was 4,246. 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.

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

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.