2026 NPPES data Endocrinology, Diabetes & Metabolism Physician NPI 1699732305 M.D.
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LEON FOGELFELD, M.D.

Endocrinology, Diabetes & Metabolism Physician in CHICAGO, Illinois. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
593
Medicare Part D claims · 102 beneficiaries · Endocrinology, Diabetes & Metabolism Physician avg: 3K
Generic prescribing
57%
generic claims · 43% brand-name · higher generic rates reduce patient out-of-pocket costs
What the federal data reveals: LEON FOGELFELD, M.D. is a Endocrinology, Diabetes & Metabolism Physician ([object Object]) practicing in CHICAGO, Illinois with a Medicare Part D prescribing footprint of 593 claims across 102 beneficiaries — 43% brand-name prescribing .

What stands out: LEON FOGELFELD, M.D. filed 593 Medicare Part D claims in 2023 across CHICAGO, Illinois. Every figure on this page comes straight from federal CMS records, with no proprietary rating applied.

Board certification likely (heuristic — not verified)

LEON FOGELFELD, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation — signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).

LEON FOGELFELD, M.D. at a glance

Quality data not reported

NPI registry status

Active

Issued 04/27/2006

NPI 1699732305

Primary specialty

Endocrinology, Diabetes & Metabolism Physician

Mid-sized

7,852 US NPIs in this specialty

Medicare Part D claims

593 78% vs specialty avg

2023 prescription claims

Specialty avg: 2,639

Specialty distribution in Illinois

How Endocrinology, Diabetes & Metabolism Physician compares to other specialties among Illinois providers

Illinois providers

Endocrinology, Diabetes & Metabolism Physician share within Illinois

1. Endocrinology, Diabetes & Metabolism Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Endocrinology, Diabetes & Metabolism Physician share within Illinois

Specialty board-certification context

Estimated specialty board-certified rate — Endocrinology, Diabetes & Metabolism Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Endocrinology, Diabetes & Metabolism Physician ABMS/AOA estimate

Est. board-certified rate (Endocrinology, Diabetes & Metabolism Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Endocrinology, Diabetes & Metabolism Physician) — ABMS / AOA estimate

The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.

Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).

LEON FOGELFELD, M.D. is a Endocrinology, Diabetes & Metabolism Physician provider practicing in CHICAGO, Illinois, according to the CMS National Plan and Provider Enumeration System (NPPES). Credentials: M.D.. NPI: 1699732305. This profile includes practice location, specialty classification, and organizational affiliations from the CMS provider registry. Provider information is self-reported to CMS and updated monthly.

LEON FOGELFELD, M.D. appears in the CMS NPPES registry as a Endocrinology, Diabetes & Metabolism Physician provider holding M.D. credentials at 1725 W HARRISON ST, CHICAGO, IL, 60612, with a listed phone of (312) 942-6163. NPI 1699732305 was issued on 04/27/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what FOGELFELD most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 593 prescription claims written by this provider, covering 102 Medicare beneficiaries and totaling roughly $271K in drug spend, split 43% brand-name and 57% generic by claim count. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Endocrinology, Diabetes & Metabolism Physician is a mid-sized specialty nationwide, with 7,852 enrolled providers across 54 states and an average of 2,639 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.

Practice Address

1725 W HARRISON ST
CHICAGO, IL 60612

Provider Details

NPI 1699732305
Specialty Endocrinology, Diabetes & Metabolism Physician
Credentials M.D.
Gender Male
NPI Issued 04/27/2006

Hospital and facility affiliations

Facilities where LEON FOGELFELD, M.D. bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" — a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.

COUNTY OF VENTURA
VENTURA, CA

Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).

License & disciplinary context — Illinois IDFPR 2023 annual report

Aggregate state board data only — NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~42K Illinois medical licensees in 2023 — they are NOT specific to LEON FOGELFELD, M.D.. To verify LEON FOGELFELD, M.D.'s current license status, search the IDFPR public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

106
Total board actions, Illinois 2023
Across 103 cases
2.52
Actions per 1,000 licensees
Illinois statewide rate
probation
Most common action type
38 cases

IDFPR publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the Illinois disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Above average

LEON FOGELFELD, M.D. — brand share 43.0%
Specialty average (est.)

43% brand-name claims vs 57% generic, on 593 2023 Medicare Part D claims.

The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

593
Total Claims
$271K
Total Drug Cost
102
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
1,338
Total Day Supply
39,782
Brand vs Generic
43% brand / 57% generic
Brand Drug Cost
$256K
Generic Drug Cost
$12K

Patient Demographics

Average Patient Age
68.8 years
Avg HCC Risk Score
1.53
Gender Split
62% female / 38% male

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

Drug Claims
Levothyroxine Sodium
52
Ozempic
Semaglutide
52
Metformin Hcl
40
Glimepiride
27
Atorvastatin Calcium
26
Alendronate Sodium
21
Jardiance
Empagliflozin
20
Methimazole
17
Hydrocortisone
15
Glipizide Er
Glipizide
14

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Endocrinology, Diabetes & Metabolism Physician Overview

How LEON FOGELFELD, M.D. fits within the Endocrinology, Diabetes & Metabolism Physician landscape nationally.

7,852
Endocrinology, Diabetes & Metabolism Physician Providers in US
54
States with Endocrinology, Diabetes & Metabolism Physician
2,639
Avg Claims per Provider

LEON FOGELFELD, M.D.'s 593 claims are below the specialty average of 2,639.

Nearby Endocrinology, Diabetes & Metabolism Physician Providers in Illinois

Other clinicians with the same primary specialty enrolled in Illinois, drawn from the same CMS NPPES roster as FOGELFELD.

Compare Endocrinology, Diabetes & Metabolism Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is LEON FOGELFELD, M.D.'s specialty?
LEON FOGELFELD, M.D. specializes in Endocrinology, Diabetes & Metabolism Physician and practices in CHICAGO, Illinois. Credentials: M.D..
How much does LEON FOGELFELD, M.D. prescribe under Medicare Part D?
In 2023, LEON FOGELFELD, M.D. wrote 593 Medicare Part D claims totaling $271K in drug costs for 102 beneficiaries.
Where is LEON FOGELFELD, M.D. located?
LEON FOGELFELD, M.D. is located at 1725 W HARRISON ST, CHICAGO, IL, 60612. Phone: (312) 942-6163.
What is LEON FOGELFELD, M.D.'s NPI number?
LEON FOGELFELD, M.D.'s National Provider Identifier (NPI) is 1699732305, issued on 04/27/2006.
Does LEON FOGELFELD, M.D. prescribe more brand-name or generic drugs?
LEON FOGELFELD, M.D.'s prescribing is 43% brand-name and 57% generic drugs by claim count, with $256K in brand drug costs.
How many Endocrinology, Diabetes & Metabolism Physician providers are there in the US?
There are 7,852 Endocrinology, Diabetes & Metabolism Physician providers across 54 states in the US. The average Endocrinology, Diabetes & Metabolism Physician provider writes 2,639 Medicare Part D claims per year.
What drugs does LEON FOGELFELD, M.D. prescribe most often?
Based on 2023 Medicare Part D data, LEON FOGELFELD, M.D.'s most frequently prescribed drugs include Levothyroxine Sodium, Ozempic, Metformin Hcl. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does LEON FOGELFELD, M.D. accept Medicare?
LEON FOGELFELD, M.D. appears in CMS Medicare data with 593 Part D claims and 102 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify LEON FOGELFELD, M.D.'s credentials?
LEON FOGELFELD, M.D.'s NPI is 1699732305 with credentials M.D.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.

Data Sources

Provider Directory
CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
Specialty Classification
NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
Prescribing Data
CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
Limitations
Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.

See our complete data methodology for details on how we collect and process government data.

Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).

Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology