Gregory O'Neal Clark, M.D.
NPI 1053363952ActiveIndividual· Internal Medicine, Endocrinology, Diabetes & Metabolism· Buffalo Grove, IL
Internal Medicine, Endocrinology, Diabetes & Metabolism (M.D.) in Buffalo Grove, Illinois, licensed in IL, with an NPI issued in May 2006. Part D covered 130 prescriptions written in 2024. Tandem Diabetes Care, Inc. was the largest of 4 companies reporting payments in 2025, $234.49 in all, mostly food and beverage.
Overview
| NPI | 1053363952 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | Yes |
| NPI issued | May 17, 2006 |
| Last updated in NPPES | Jul 26, 2023 |
| Certified by provider | Jul 26, 2023 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Endocrinology, Diabetes & Metabolism Primary | 207RE0101X | 336.093729 | IL |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 10, 2026 | No match | — |
| New York OMIG · Nov 10, 2026 | No match | — |
| Ohio Medicaid · Nov 10, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 10, 2026 | No match | — |
| Washington HCA · Nov 10, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Not in the public enrollment file of Oct 1, 2026 |
|---|---|
| Opt-out | Past opt-out Oct 22, 2020 – Oct 22, 2026 |
| Can order and refer | Yes |
Part D prescriptions in 2024
| Prescriptions (claims) | 130 · 170 30-day fills |
|---|---|
| Total drug cost | $41,724 |
Industry payments (Open Payments)
- 2025$234.49 · 5 payments from 4 companies
- 2024$426.31 · 8 payments from 4 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Tandem Diabetes Care, Inc. | $124.87 | 1 |
| Mannkind Corporation | $55.90 | 2 |
| Sequel Med Tech, LLC | $36.93 | 1 |
| Novo Nordisk Inc | $16.79 | 1 |
What the 2025 payments were for
- Food and Beverage$234.49 · 5 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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