John Leff, MD
NPI 1689693327 · Endocrinology, Diabetes & Metabolism Physician · Brooklyn, NY
John Leff, MD is a Endocrinology, Diabetes & Metabolism Physician provider in Brooklyn, NY (NPI 1689693327).
Provider details
- NPI number
- 1689693327
- Entity type
- Individual
- Primary specialty
- Endocrinology, Diabetes & Metabolism PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- 143472 (NY)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
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 methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-07-19
- Last updated
- 2012-01-17
Frequently asked questions
- What is John Leff's NPI number?
- John Leff's National Provider Identifier (NPI) is 1689693327, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Leff's specialty?
- John Leff is listed in the NPPES registry with a primary specialty of Endocrinology, Diabetes & Metabolism Physician (Allopathic & Osteopathic Physicians).
- Where is John Leff located?
- John Leff's practice location on file with NPPES is Lutheran Medical Center, Brooklyn, NY 11220.
- What is John Leff's phone number?
- The practice phone number listed in the NPPES registry for John Leff is (718) 630-7369.
- Is John Leff's NPI active?
- Yes — John Leff's NPI (1689693327) is active in the NPPES registry as of the last update on 2012-01-17.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.