Quick answers
- Does Oliver L. Ong accept Medicare assignment?
- Yes. Medicare's clinician data says Oliver L. Ong accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Oliver L. Ong see?
- In 2024, CMS data shows 650 Original Medicare patients and 1,459 services for Oliver L. Ong. This counts Original Medicare only and measures volume, not quality.
- What is Oliver L. Ong's NPI number?
- 1811951734. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Oliver L. Ong, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 650 |
|---|---|
| Services billed to Medicare | 1,459 |
| Different services or procedures | 14 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)697 services
- Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes (99231)457 services
- New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more (99204)85 services
- Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)80 services
- Telephone medical discussion with physician, 11-20 minutes (99442)45 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- High cholesterol75%
- Diabetes75%
- Arthritis69%
- Ischemic heart disease56%
- Chronic kidney disease43%
Hospitals where Oliver L. Ong works
Medicare's Facility Affiliation Data lists Oliver L. Ong at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Adventist Health Simi ValleySimi Valley, CA · Acute Care Hospital · Medicare rating: 2 of 5 stars · Emergency services: listed by Medicare · CCN 050236
- Glendale Adventist Medical CenterGlendale, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050239
- USC Verdugo Hills HospitalGlendale, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050124
Practice locations
Addresses where Oliver L. Ong is enrolled with Medicare (CMS data updated October 2, 2026).
- 124 Macaw LnSimi Valley, CA 93065 (805) 306‑0304
- 2750 Sycamore DrSimi Valley, CA 93065
- 2950 Sycamore DrSimi Valley, CA 93065
- 544 N Glendale AveGlendale, CA 91206 (818) 265‑2242
- 544 N Glendale Ave, Suite BGlendale, CA 91206 (818) 265‑2242
Group practices
Medicare enrollment lists Oliver L. Ong as a member of this group (CMS data updated October 2, 2026).
- Adventist Health Physicians Network628 clinicians in the group
Specialties
- Endocrinologyprimary
- Internal Medicinealso
Other endocrinologists in Simi Valley
Clinicians with the same Medicare primary specialty in Simi Valley, CA — not a recommendation.
Other clinicians in Adventist Health Physicians Network
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | George Washington University School Of Medicine |
| Graduation year | 1996 (30 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1811951734 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians