BARRY IZENSTEIN, M.D. appears in the CMS NPPES registry as a Endocrinology, Diabetes & Metabolism Physician provider holding M.D. credentials at 2 MEDICAL CENTER DR, SPRINGFIELD, MA, 01107, with a listed phone of (413) 734-4667. NPI 1346237583 was issued on 10/03/2005. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what IZENSTEIN most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 8,172 prescription claims written by this provider, covering 657 Medicare beneficiaries and totaling roughly $2.2 million in drug spend, split 24% brand-name and 76% generic by claim count, with an opioid prescribing rate of 1.1%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 79.7715/100 for the 2023 performance year (Quality 82.1497, Cost 56.372), compared with the national average of 83.1.

Endocrinology, Diabetes & Metabolism Physician is a mid-sized specialty nationwide, with 7,852 enrolled providers across 54 states and an average of 2,639 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.