MS. DIANE GRASSI NP
NPI 1063917136
Nurse Practitioner - Adult Health in Smithtown, NY
About Ms. Diane Grassi Np NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MS. DIANE GRASSI NP (NPI 1063917136) is an individual adult health provider in Smithtown, New York, licensed in New York (F308295-1) and active in the NPI registry since March 2018. She is enrolled in Medicare PECOS, is affiliated with North Shore University Hospital, and is a graduate of State University Of New York At Stony Brook, School Of Medicine (2016).
NPPES Registry Identity
Specialties & Licenses 2
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Ms. Diane Grassi Np is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
2Medicare enrollment records show Diane Grassi reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Smithtown, NY 11787
- Reassigned Medicare billing, New York enrollment
- 6 clinicians in this Medicare group
Great Neck, NY 11021
- Reassigned Medicare billing, New York enrollment
- 9,353 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
North Shore University Hospital
Acute Care Hospitals · Manhasset, NYPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 11787 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Referred Medical Equipment & Supplies CMS DME claims
Durable medical equipment, devices and supplies this provider ordered from DME suppliers for patients, from Medicare fee-for-service claims.
Other Providers at the Same Location NPPES 6
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
SMITHTOWN, NY 11787
SMITHTOWN, NY 11787
SMITHTOWN, NY 11787
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Diane Grassi's NPI number?
The NPI number for Diane Grassi is 1063917136. It was assigned to this individual provider in the NPPES registry on March 29, 2018.
Where is Diane Grassi located?
Diane Grassi practices at 285 E Main St, Smithtown, NY 11787. The listed phone number is (631) 656-0874.
What is Diane Grassi's specialty?
The primary specialty registered for this NPI is Nurse Practitioner, specializing in Adult Health, with taxonomy code 363LA2200X.
Is Diane Grassi enrolled in Medicare?
Yes. Diane Grassi is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Diane Grassi's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Diane Grassi reassigns Medicare benefits to 2 organizations: Middle Country Endocrinology, PC (Smithtown, NY) and North Shore-Lij Medical PC (Great Neck, NY). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Diane Grassi's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
Is Diane Grassi affiliated with any hospitals?
According to CMS data, Diane Grassi is affiliated with North Shore University Hospital.
When was this NPI record last updated?
The NPPES record for Diane Grassi was last updated on January 7, 2019. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 7 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Ms. Diane Grassi, NP · NPI 1063917136
Adult Health physician in Smithtown, New York. Individual provider, active in the CMS NPPES registry since March 29, 2018.
## Identity
- **NPI:** 1063917136 (Entity type: Individual)
- **Enumerated:** March 29, 2018
- **Primary specialty:** Nurse Practitioner - Adult Health · taxonomy 363LA2200X
- **State license:** F308295-1 (New York)
- **Sole proprietor:** Yes
## Practice location
- **Address:** 285 E MAIN ST, Smithtown, NY 11787-2978
- **Phone:** (631) 656-0874
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 2 organizations under Medicare reassignment (form CMS-855R): Middle Country Endocrinology, PC (NPI 1295068930, Smithtown, NY); North Shore-Lij Medical PC (NPI 1053688572, Great Neck, NY) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** State University Of New York At Stony Brook, School Of Medicine, class of 2016
## Record status
- **NPPES last updated:** January 7, 2019
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Source: [NPI Profile](https://npiprofile.com/npi/1063917136) · Data from the CMS NPPES public registry.