James A. Mack, MD
Endocrinology, Diabetes & Metabolism Physician · Billings, MT
James A. Mack, MD is an endocrinology, diabetes & metabolism physician with a practice address in Billings, Montana, and NPI 1669575445, issued on Sep 6, 2006. Check the license (Montana 8739, as entered in NPPES) on the Montana Board of Medical Examiners; the Medicare figures below come from public CMS files.
- Name
- James A. Mack
- Credential
- MD
- Primary taxonomy
- Endocrinology, Diabetes & Metabolism Physician 207RE0101X
- License number
- 8739 MT
Self-reported in NPPES; status is on the state search - Practice location
- 1045 N 30TH St, Billings, MT 59101
- Phone
- (406) 238-2500
- Enumerated
- Sep 6, 2006
- Record last updated
- Feb 10, 2022
- Entity
- Type 1 · individual
8 nearest endocrinology, diabetes & metabolism physician records → All 23 in Montana → Look up another NPI →
Also registered at 1045 N 30TH St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Xiu Ying AuEndocrinology, Diabetes & Metabolism Physician1659923712
- Gabriel Blomquist, P.A.Medical Physician Assistant1659772176
- Christa Boggis-Delacruz, MDObstetrics & Gynecology Physician1215642665
- Reed Christensen, M.D.Endocrinology, Diabetes & Metabolism Physician1902882673
- Brenda FlahertyStudent in an Organized Health Care Education/Training Program1942657762
- Landon Horst, RDRegistered Dietitian1124795562
Verify James A. Mack in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMontana Board of Medical Examiners
Search for license 8739Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average endocrinology, diabetes & metabolism physician in 2024
15 Medicare Part D claims, against an average of 2,630 among the 8,223 providers of this specialty who prescribed in Part D.
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 94.3 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
James A. Mack among 23 endocrinology, diabetes & metabolism physician records in Montana
James A. Mack, MD is one of 23 endocrinology, diabetes & metabolism physician records with a practice address in Montana. 83% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 17% of them.
- NPI issued2006 · 17% of these records are older, 39% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileNo · 65% of these records are
- Record last updated2022 · 26% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RE0101X and a Montana practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Endocrinology, Diabetes & Metabolism Physician providers in Montana
There are 23 endocrinology, diabetes & metabolism physician records in Montana.
All 23 in Montana → Every provider in Billings → Endocrinology, Diabetes & Metabolism Physician nationwide →
The 8 endocrinology, diabetes & metabolism physician records with the nearest ZIP codes
- Xiu Ying AuBillings, MT 591011659923712
- Reed Christensen, M.D.Billings, MT 591011902882673
- David Gaitonde, MDBillings, MT 591011902964638
- David Johnson, MDBillings, MT 591011972544617
- Lauren Kleess, M.D.Billings, MT 591011346689544
- Christopher Sorli, MDBillings, MT 591011972537660
- Barry Cohan, M.D.Great Falls, MT 594051477646750
- Heidi Peynado De PenaGreat Falls, MT 594051265883607
Common questions
What is James A. Mack, MD's NPI number?
James A. Mack, MD's National Provider Identifier (NPI) is 1669575445, issued on Sep 6, 2006. An NPI identifies a provider in billing; it is not a license.
Where is James A. Mack, MD located?
The NPPES record lists a practice address at 1045 N 30TH St, Billings, MT, 59101. Phone: (406) 238-2500. Providers update this record themselves, so call before visiting.
How can I verify James A. Mack, MD's license?
NPPES lists Montana license number 8739, as entered by the provider. Search the Montana Board of Medical Examiners at https://ebiz.mt.gov/POL/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does James A. Mack, MD prescribe under Medicare Part D?
In 2024, James A. Mack, MD had 15 Medicare Part D claims; the average among endocrinology, diabetes & metabolism physician prescribers was 2,630. Part D covers Medicare prescriptions only.
What is James A. Mack, MD's MIPS final score?
The 2023 MIPS final score is 94.3 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.