Gregorio Guillen, M.D
NPI 1538252226 · Geriatric Medicine (Internal Medicine) Physician · Perth Amboy, NJ
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Gregorio Guillen, M.D is a Geriatric Medicine (Internal Medicine) Physician provider in Perth Amboy, NJ (NPI 1538252226).
Provider details
- NPI number
- 1538252226
- Entity type
- Individual
- Primary specialty
- Geriatric Medicine (Internal Medicine) PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D
- Sex
- Male
- Sole proprietor
- Yes
- License
- MA56159 (NJ)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
1,144 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
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 .
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) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 336 | $140 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 229 | $100 |
| Advance Care Planning, First 30 Minutes99497 | 119 | $88 |
| Annual Wellness Visit, Includes a Personalized Prevention Plan of Service (pps), Subsequent VisitG0439 | 100 | $142 |
| Annual Depression Screening, 5 to 15 MinutesG0444 | 97 | $21 |
| Administration of Influenza Virus VaccineG0008 | 60 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 188 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 829 | 279 |
| Omeprazole | 516 | 155 |
| Amlodipine Besylate | 495 | 176 |
| Metoprolol Succinate | 364 | 104 |
| Gabapentin | 322 | 116 |
| Metformin Hcl | 312 | 98 |
| Albuterol Sulfate |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$1,761 across 105 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-10-02
- Last updated
- 2013-08-06
Frequently asked questions
- What is Gregorio Guillen's NPI number?
- Gregorio Guillen's National Provider Identifier (NPI) is 1538252226, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Gregorio Guillen's specialty?
- Gregorio Guillen is listed in the NPPES registry with a primary specialty of Geriatric Medicine (Internal Medicine) Physician (Allopathic & Osteopathic Physicians).
- Where is Gregorio Guillen located?
- Gregorio Guillen's practice location on file with NPPES is 400 State St. Suite 2, Perth Amboy, NJ 08861.
- What is Gregorio Guillen's phone number?
- The practice phone number listed in the NPPES registry for Gregorio Guillen is (732) 442-6020.
- Does Gregorio Guillen accept Medicare?
- Gregorio Guillen is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Gregorio Guillen's NPI active?
- Yes — Gregorio Guillen's NPI (1538252226) is active in the NPPES registry as of the last update on 2013-08-06.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.