Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Gretchen J Diefenbach, PHD

Clinical Psychologist in Hartford, CT · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1154337939

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Registry record

Entity type Individual (Type 1)

Name Gretchen J Diefenbach

Credential PHD

Sex Female

Practice address 200 Retreat Avenue, Hartford Hospital Anxiety Disorders Center, Hartford, CT, 06106

Phone (860) 545-7685

Enumeration date Jul 31, 2006

Last updated in NPPES Feb 21, 2008

Taxonomy & licenses

103TC0700X Clinical Psychologist Behavioral Health & Social Service Providers · License 002370 (CT) Primary

PHD · Doctor of Philosophy: A doctoral degree; in healthcare often held by clinical psychologists and researchers. About the PHD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Where does Gretchen Diefenbach practice?

The practice location on file with NPPES is in Hartford, CT. Providers can have multiple locations; NPPES lists the primary practice address.

What is the NPI number for Gretchen Diefenbach?

The National Provider Identifier (NPI) for Gretchen Diefenbach is 1154337939, a Type 1 (individual) record in the CMS NPPES registry.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2008-02-21.