Dr. Elizabeth R. Grethen, MD

Concierge Endocrinology physician, Carmel, IN

Impact Endocrinology

Dr. Elizabeth Grethen is a Concierge Endocrinology physician in Carmel who opened Impact Endocrinology, a direct care practice.

188 W. Carmel Drive, Carmel, IN 46032
At a glance
Practice model
Direct care membership, not in network with any insurance
Membership
$110 a month if paid monthly
Board certification
Double board certified, endocrinology, diabetes and metabolism
Insurance
Not in network with any insurance, including Medicare
Telehealth
Telehealth visits for members

Facts on this page last checked November 2026. How we check doctors

About Dr. Grethen

Dr. Grethen is double board certified in endocrinology, diabetes and metabolism. She earned her bachelor's degree in Neurobiology and Behavior at Cornell University in Ithaca, New York, and her medical degree at Loyola University Stritch School of Medicine. She completed her Internal Medicine residency at Indiana University in Indianapolis.

During fellowship she published the results of her clinical research on bone effects of metabolic disease and obesity. She worked at Ascension St. Vincent for many years and took part in several medical committees there to improve care for people with diabetes. She then opened her own practice, Impact Endocrinology.

She says Impact Endocrinology is the first direct care endocrinology practice in Indiana. She believes in taking time with each patient to learn what works for that person. She also took part in a medical service trip to India, providing care to residents of remote villages in the Himalayas.

Membership and fees

Membership at Impact Endocrinology is $110 if paid monthly, $630 if paid every 6 months or $1,240 if paid every 12 months.

Membership includes unlimited appointments, priority scheduling, complimentary pump and CGM downloads and unlimited direct communication with Dr. Grethen by portal, text or phone.

Without membership, a new patient visit costs $395 for a 60+ minute initial appointment, and a 30-minute in-person follow-up costs $265.

Fees vary by plan. Ask the practice.

Services

Diabetes Thyroid disorders Osteoporosis Calcium-related disorders Adrenal and pituitary disease PCOS Discounted lab tests for patients who pay directly
What endocrinology doctors commonly treat

Education and credentials

Degree
MD
College
Cornell University (Neurobiology and Behavior)
Medical school
Loyola University Stritch School of Medicine
Residency
Internal Medicine, Indiana University, Indianapolis
Board certification
Double board certified in endocrinology, diabetes and metabolism
License
Indiana
Board actions
Good standing (checked Nov 2026) None on record Verify with the Indiana Medical Licensing Board
NPI
1962660522

Hospital and practice affiliations

Opened Impact Endocrinology

Location

188 W. Carmel Drive, Carmel, IN 46032
Impact Endocrinology practice page
Directions

Recognition and research

Media and books

Featured in a Current in Carmel news story on the opening of Impact Endocrinology

Teaching and research roles

Has taught many students and resident physicians over the years
Published clinical research on bone effects of metabolic disease and obesity during fellowship

Publications

"Serum leptin, parathyroid hormone, 1,25-dihydroxyvitamin D, fibroblast growth factor 23, bone alkaline phosphatase, and sclerostin relationships in obesity" in The Journal of Clinical Endocrinology and Metabolism (2012)
"Vitamin D and hyperparathyroidism in obesity" in The Journal of Clinical Endocrinology and Metabolism (2011)
"MON-LB059 A Family Reunion at the Geneticist's Office: Hypercalcemia as Presenting Symptoms of MEN1" in Journal of the Endocrine Society (2019)

Patient reviews

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Questions patients ask

Does Dr. Grethen take insurance, or offer a membership?

Impact Endocrinology is a direct care endocrinology practice with a membership program. Dr. Grethen is not in network with any insurance, including Medicare, and patients pay directly at the time of the appointment. She has negotiated significant discounts on lab tests for patients who wish to pay directly.

How much does a membership at Impact Endocrinology cost?

Membership is $110 if paid monthly, $630 if paid every 6 months or $1,240 if paid every 12 months. A rejoin fee of $200 applies to patients who rejoin membership after a break.

How much does a visit cost without a membership?

A new patient visit costs $395 and is a 60+ minute initial appointment to address endocrine concerns. A non-membership in-person follow-up costs $265 for 30 minutes or $325 for 60 minutes, and a non-membership virtual follow-up of 30 minutes costs $225.

Is Dr. Grethen board certified?

Dr. Grethen is double board certified in endocrinology, diabetes and metabolism.

Where did Dr. Grethen train?

She earned her medical degree at Loyola University Stritch School of Medicine. She completed her Internal Medicine residency at Indiana University in Indianapolis.

Where is Dr. Grethen's office?

Impact Endocrinology is at 188 W. Carmel Drive in Carmel, IN.

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