Gerard John Diefes, M.D.
NPI 1417948951ActiveIndividual· Internal Medicine, Pulmonary Disease· Wynnewood, PA
Internal Medicine, Pulmonary Disease (M.D.) in Wynnewood, Pennsylvania, trained at Hahnemann University College of Medicine (class of 1992). Their prescriptions cost Medicare Part D more than their services did: $568,479 for 1,545 claims, against $153,740 paid for services in 2024. Glaxosmithkline, LLC. was the largest of 16 companies reporting payments in 2025, $2,981 in all, mostly food and beverage.
Overview
| NPI | 1417948951 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | No |
| NPI issued | Nov 3, 2005 |
| Last updated in NPPES | May 20, 2025 |
| Certified by provider | May 20, 2025 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Pulmonary Disease Primary | 207RP1001X | MD056949L | PA |
| Internal Medicine, Critical Care Medicine | 207RC0200X | MD056949L | PA |
| Internal Medicine, Sleep Medicine | 207RS0012X | MD056949L | PA |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 4, 2026 | No match | — |
| New York OMIG · Nov 4, 2026 | No match | — |
| Ohio Medicaid · Nov 4, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 4, 2026 | No match | — |
| Washington HCA · Nov 4, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Pulmonary Disease (PA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 314 |
|---|---|
| Services billed | 1,669 across 21 procedure codes |
| Paid by Medicare | $153,740 |
Part D prescriptions in 2024
| Prescriptions (claims) | 1,545 · 1,944 30-day fills |
|---|---|
| Patients | 230 |
| Total drug cost | $568,479 |
Education and affiliations
| Medical school | Hahnemann University College of Medicine |
|---|---|
| Graduation year | 1992 |
| Medicare specialty | Pulmonary Disease |
| Secondary specialties | Critical Care (Intensivists), Internal Medicine, Sleep Medicine |
| Telehealth | Offers telehealth |
Medical group
- Advocare, LLCHaddonfield, NJ · 386 clinicians
Hospital affiliations
- Chester County HospitalWest Chester, PA
- Hospital of Univ of PennsylvaniaPhiladelphia, PA
- Main Line Hospital LankenauWynnewood, PA
- Paoli HospitalPaoli, PA
- St Mary Medical CenterLanghorne, PA
Industry payments (Open Payments)
- 2025$2,981 · 144 payments from 16 companies
- 2024$1,228 · 55 payments from 12 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Glaxosmithkline, LLC. | $648.40 | 37 |
| Astrazeneca Pharmaceuticals LP | $627.02 | 36 |
| Jazz Pharmaceuticals Inc. | $289.68 | 7 |
| Regeneron Healthcare Solutions, Inc. | $223.93 | 12 |
| Axsome Therapeutics, Inc. | $213.66 | 10 |
What the 2025 payments were for
- Food and Beverage$2,885 · 143 payments
- Education$95.99 · 1 payment
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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