Gretta Colby, MD
NPI 1306587639 · Internal Medicine Physician · Milwaukee, WI
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Gretta Colby, MD is a Internal Medicine Physician provider in Milwaukee, WI (NPI 1306587639).
Provider details
- NPI number
- 1306587639
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- Yes
- License
- 83738-20 (WI)
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
4 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
- 2022-04-01
- Last updated
- 2025-09-18
- Certified
- 2025-09-18
Frequently asked questions
- What is Gretta Colby's NPI number?
- Gretta Colby's National Provider Identifier (NPI) is 1306587639, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Gretta Colby's specialty?
- Gretta Colby is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Gretta Colby located?
- Gretta Colby's practice location on file with NPPES is 945 N 12th St, Milwaukee, WI 53233-1305.
- What is Gretta Colby's phone number?
- The practice phone number listed in the NPPES registry for Gretta Colby is (414) 219-7427.
- Does Gretta Colby accept Medicare?
- Gretta Colby is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Gretta Colby's NPI active?
- Yes — Gretta Colby's NPI (1306587639) is active in the NPPES registry as of the last update on 2025-09-18.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.