Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Mark Joseph O'Connor, MD

Individual provider Endocrinology, Diabetes & Metabolism Physician · NPI 1518300284

Mark Joseph O'Connor, MD is an Endocrinology in Worcester, Massachusetts. Graduated from University of Massachusetts Medical School in 2013, 13 years ago. Practices with Umass Memorial Medical Group Inc, a 2,467-clinician group, works from 2 locations, accepts Medicare assignment and offers telehealth. Licensed in Massachusetts.

Years since qualifying
13
Trained at
University of Massachusetts Medical School
Licensed in
MA
In the registry since
2013
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

55 Lake Ave N
Worcester, MA 01655-0002
Phone: (508) 334-3206
Fax: (774) 442-4668
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 100 Hospital Rd, Leominster, MA 01453-2253 — (978) 466-4580

Specialties & licences

Endocrinology, Diabetes & Metabolism Physician (primary) Taxonomy 207RE0101X · Licence 266640 (MA)

Record details

NPI number1518300284
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedApril 12, 2013
Last updated in NPPESMarch 30, 2021
Certification dateMarch 30, 2021

Medicare enrollment

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

Medicare specialtyENDOCRINOLOGY
Also practisesINTERNAL MEDICINE
Medical schoolUNIVERSITY OF MASSACHUSETTS MEDICAL SCHOOL
Graduated 2013 (13 years in practice)
Group practice Umass Memorial Medical Group Inc — 2467 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services

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