JOANNA DIEL-MARTIN, NP appears in the CMS NPPES registry as a Nurse Practitioner provider holding NP credentials at 1179 N MCDOWELL BLVD, PETALUMA, CA, 94954, with a listed phone of (707) 559-7500. NPI 1932759461 was issued on 09/17/2019. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what DIEL-MARTIN 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 665 prescription claims written by this provider, covering 104 Medicare beneficiaries and totaling roughly $112K in drug spend. 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.

Nurse Practitioner is a high-volume specialty nationwide, with 87,227 enrolled providers across 56 states and an average of 1,084 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.