Dr William James Giesen, MD - Medicare Internal Medicine in Darien, CT

Dr William James Giesen, MD is a medicare enrolled "Internal Medicine" physician in Darien, Connecticut. He went to Georgetown University School Of Medicine and graduated in 1975 and has 49 years of diverse experience with area of expertise as Internal Medicine. His current practice location is 1500 Post Rd., Darien, Connecticut. You can reach out to his office (for appointments etc.) via phone at (203) 655-2516.

Dr William James Giesen is licensed to practice in Connecticut (license number CT023721) and he also participates in the medicare program. He accepts medicare assignments (which means he accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance) and his NPI Number is 1124104724.

Contact Information

Dr William James Giesen, MD
1500 Post Rd.,
Darien, CT 06820
(203) 655-2516
(203) 656-3665

Map and Direction




Physician's Profile

Full NameDr William James Giesen
GenderMale
SpecialityInternal Medicine
Experience49 Years
Location1500 Post Rd., Darien, Connecticut
Accepts Medicare AssignmentsYes. He accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance.
  Medical Education and Training:
  • Dr William James Giesen attended and graduated from Georgetown University School Of Medicine in 1975
  NPI Data:
  • NPI Number: 1124104724
  • Provider Enumeration Date: 10/27/2006
  • Last Update Date: 05/09/2016
  Medicare PECOS Information:
  • PECOS PAC ID: 2567367584
  • Enrollment ID: I20031203000549

Medical Identifiers

Medical identifiers for Dr William James Giesen such as npi, medicare ID, medicare PIN, medicaid, etc.
IdentifierTypeStateIssuer
1124104724NPI-NPPES
061258283OtherGUARDIAN
0697273OtherUS HEALTHCARE
4111798OtherAETNA
061258283OtherCHP
237210OtherCONNECTICARE

Medical Taxonomies and Licenses

TaxonomyTypeLicense (State)Status
207R00000XInternal Medicine CT023721 (Connecticut)Primary

Medical Facilities Affiliation

Facility NameLocationFacility Type
Stamford HospitalStamford, CTHospital

Medicare Part D Prescriber Enrollment

Any physician or other eligible professional who prescribes Part D drugs must either enroll in the Medicare program or opt out in order to prescribe drugs to their patients with Part D prescription drug benefit plans. Dr William James Giesen is enrolled with medicare and thus, if eligible, can prescribe medicare part D drugs to patients with medicare part D benefits.

Mailing Address and Practice Location

Mailing AddressPractice Location Address
Dr William James Giesen, MD
1500 Post Rd,
Darien, CT 06820

Ph: (203) 655-2516
Dr William James Giesen, MD
1500 Post Rd.,
Darien, CT 06820

Ph: (203) 655-2516

Reviews and Comments


Internal Medicine Doctors in Darien, CT

Dr. Victor John William Lawrence, M.D.
Internal Medicine
Medicare: Not Enrolled in Medicare
Practice Location: 29 Thomasina Ln, Darien, CT 06820
Phone: 203-655-4319    Fax: 203-655-4319
Dr. Amanda C Collins- Baine, M.D.
Internal Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 53 Old Kings Hwy N Ste 205, Darien, CT 06820
Phone: 203-286-5604    Fax: 475-328-9072
Margaret Baran,
Internal Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 1500 Post Rd Ste 100, Darien, CT 06820
Phone: 203-655-8749    Fax: 203-655-0701
Dr. Robert A Lindberg, M.D.
Internal Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 1500 Post Rd, Darien, CT 06820
Phone: 203-656-1012    Fax: 203-656-1005
Sujana Sunkara, MD
Internal Medicine
Medicare: Medicare Enrolled
Practice Location: 1500 Post Rd, Darien, CT 06820
Phone: 203-655-8749    Fax: 203-656-0701
Dr. Susan M Collins, M.D.
Internal Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 1500 Post Rd, First Floor, Darien, CT 06820
Phone: 203-655-8749    Fax: 203-656-0701

Medicare Program: Medicare is a federal government program which provides health insurance to people who are 65 or older. This program also covers certain younger people with disabilities (who receive Social Security Disability Insurance - SSDI), and people with End-Stage Renal Disease (permanent kidney failure requiring dialysis or a transplant, sometimes called ESRD.

Medicare Assignment: Assignment means that your doctor, provider, or supplier agrees (or is required by law) to accept the Medicare-approved amount as full payment for covered services. Most doctors, providers, and suppliers accept assignment, but you should always check to make sure. Participating providers have signed an agreement to accept assignment for all Medicare-covered services.

NPI Number: The National Provider Identifier (NPI) is a unique identification number for covered health care providers. The NPI must be used in lieu of legacy provider identifiers in the HIPAA standards transactions. Covered health care providers and all health plans and health care clearinghouses must use the NPIs in the administrative and financial transactions adopted under HIPAA (Health Insurance Portability and Accountability Act).

Our Data: Information on www.medicarelist.com is built using data sources published by Centers for Medicare & Medicaid Services (CMS) under Freedom of Information Act (FOIA). The information disclosed on the NPI Registry are FOIA-disclosable and are required to be disclosed under the FOIA and the eFOIA amendments to the FOIA. There is no way to 'opt out' or 'suppress' the NPPES record data for health care providers with active NPIs.