Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mark D Diamond, D.O.
Hospitalist Physician in Joliet, IL · enumerated 2006.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1265402804
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Registry record
Entity type Individual (Type 1)
Name Mark D Diamond
Credential D.O.
Sex Male
Practice address 2100 Glenwood Ave, Joliet, IL, 60435
Phone (815) 725-2121
Fax (815) 744-3117
Enumeration date Jan 25, 2006
Last updated in NPPES Aug 7, 2023
Taxonomy & licenses
207R00000X Internal Medicine Physician Allopathic & Osteopathic Physicians · License 036091440 (IL) Secondary
208M00000X Hospitalist Physician Allopathic & Osteopathic Physicians · License 036091440 (IL) Primary
DO · Doctor of Osteopathic Medicine: A fully licensed physician trained in osteopathic medical schools, with the same practice rights as an MD.
About the DO credential
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| 036091440 | Medicaid | IL | - |
What is an NPI number?
A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.
Frequently asked questions
What is the NPI number for Mark Diamond?
The National Provider Identifier (NPI) for Mark Diamond is 1265402804, a Type 1 (individual) record in the CMS NPPES registry.
Where does Mark Diamond practice?
The practice location on file with NPPES is in Joliet, IL. Providers can have multiple locations; NPPES lists the primary practice address.
Other providers at this practice address
Browse all → Margaret Zabiega Hospitalist Physician · Joliet, IL NPI 1578564654 David Choe Diagnostic Radiology Physician · Joliet, IL NPI 1477555027 Steven Nemeth Family Medicine Physician · Joliet, IL NPI 1336137314 Nisha Patel Diagnostic Radiology Physician · Joliet, IL NPI 1407828882 Asavari Javeri Family Medicine Physician · Joliet, IL NPI 1073558466 Vairavan Viswanathan Internal Medicine Physician · Joliet, IL NPI 1326083890 Mony Sarcu Internal Medicine Physician · Joliet, IL NPI 1760427876 Katherine Spangenberg Internal Medicine Physician · Joliet, IL NPI 1942246954
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2023-08-07.