Gregory Shimizu, MD
NPI 1154492130 · Internal Medicine Physician · Fontana, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Gregory Shimizu, MD is a Internal Medicine Physician provider in Fontana, CA (NPI 1154492130).
Provider details
- NPI number
- 1154492130
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- G67137 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
19 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
910 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 357 | $119 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 232 | $79 |
| Advance Care Planning, First 30 Minutes99497 | 154 | $76 |
| Hospital Discharge Day Management, More Than 30 Minutes99239 | 94 | $116 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes99223 | 58 | $174 |
| Smoking and Tobacco Use Intensive Counseling, More Than 10 Minutes99407 | 15 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-11-13
- Last updated
- 2008-09-23
Frequently asked questions
- What is Gregory Shimizu's NPI number?
- Gregory Shimizu's National Provider Identifier (NPI) is 1154492130, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Gregory Shimizu's specialty?
- Gregory Shimizu is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Gregory Shimizu located?
- Gregory Shimizu's practice location on file with NPPES is 9961 Sierra Ave, Fontana, CA 92335-6720.
- What is Gregory Shimizu's phone number?
- The practice phone number listed in the NPPES registry for Gregory Shimizu is (909) 427-3910.
- Does Gregory Shimizu accept Medicare?
- Gregory Shimizu is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Gregory Shimizu's NPI active?
- Yes — Gregory Shimizu's NPI (1154492130) is active in the NPPES registry as of the last update on 2008-09-23.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.