Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mark D Diamond, DO

Individual provider Internal Medicine Physician · NPI 1265402804

Mark D Diamond, DO practises Internal Medicine in Joliet, Illinois. Graduated from Chicago College of Osteopathy in 1993, 33 years ago. Practices with Dupage Medical Group Ltd, a 1,328-clinician group and accepts Medicare assignment. Licensed in Illinois.

Years since qualifying
33
Trained at
Chicago College of Osteopathy
Licensed in
IL
In the registry since
2006
Specialties on file
2
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

2100 Glenwood Ave
Joliet, IL 60435-5487
Phone: (815) 725-2121
Fax: (815) 744-3117
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Hospitalist Physician (primary) Taxonomy 208M00000X · Licence 036091440 (IL)
Internal Medicine Physician Taxonomy 207R00000X · Licence 036091440 (IL)

Record details

NPI number1265402804
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedJanuary 25, 2006
Last updated in NPPESAugust 7, 2023
Certification dateAugust 7, 2023

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyINTERNAL MEDICINE
Medical schoolCHICAGO COLLEGE OF OSTEOPATHY
Graduated 1993 (33 years in practice)
Group practice Dupage Medical Group Ltd — 1328 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients336
Services billed 1,096 a service is one billed item, such as a visit, a test or a procedure
Average patient age80

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Dupage Medical Group Ltd

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1328 clinicians in the practice; 12 are shown here.

Other providers in Joliet