Actively Recruiting
Metformin and Insulin Resistance in Women Completing Chemotherapy for Stage I-III Breast Cancer
Led by City of Hope Medical Center · Updated on 2026-01-22
200
Participants Needed
3
Research Sites
N/A
Total Duration
On this page
Sponsors
C
City of Hope Medical Center
Lead Sponsor
N
National Cancer Institute (NCI)
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are studying how often women develop insulin resistance and type-2 diabetes after chemotherapy for stage I-III breast cancer. The trial compares metformin combined with usual care to usual care alone for treating insulin resistance, a condition where cells do not respond well to insulin. Insulin resistance raises the risk of diabetes and heart disease, and higher insulin levels have been linked to aggressive breast cancer. Metformin helps reduce blood sugar by lowering glucose release from the liver and increasing its use, but its effects after chemotherapy in breast cancer survivors are not yet known. Participants are randomly assigned to one of two groups. One group receives standard healthy diet and exercise education plus extended-release metformin taken orally once daily for 12 months, unless disease progression or unacceptable side effects occur. The other group receives only the standard diet and exercise education. Blood samples are collected from all participants throughout the study to monitor various health markers. After completing treatment, participants are followed up at 30 days and again at 12 months. During the trial, participants will have blood tests to measure hemoglobin A1c (HgbA1c) levels at baseline, 3, 6, 12, and 24 months to assess blood sugar control. Researchers also explore metformin's effects on epigenetic changes and inflammatory markers. Participants complete questionnaires and receive educational materials. The main outcome is normalization of HgbA1c within 12 months. The total study duration includes 12 months of treatment plus follow-up visits, with continuous monitoring for safety and disease status.
CONDITIONS
Brief Title
Metformin for the Treatment of Insulin Resistance in Women With Stage I-III Breast Cancer Completing Chemotherapy
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Signed informed consent
- Agreement to blood draws (about 26 mL) for labs at baseline, 3, 6, 12, and 24 months
- Age 18 years or older
- Female sex assigned at birth
- Ability to read and understand English or Spanish
- Diagnosis of estrogen receptor-negative or HER2 wild-type or amplified invasive breast cancer stages I-III
- Completed systemic breast cancer treatment within 90 days to 5 years and are disease free
- Women using weight loss drugs like semaglutide before diagnosis are eligible and may continue during the study
You will not qualify if you...
- Currently taking metformin or other oral antidiabetic medications
- Taking tamoxifen or aromatase inhibitors
- Allergy or hypersensitivity to metformin
- Acute or chronic kidney problems with low filtration rate or related liver transplant period
- Previously diagnosed with type 1 or type 2 diabetes
- Pregnant or within 1 year after pregnancy and lactation
- Having another active cancer that might interfere with study safety or results
- Any condition judged unsafe for participation by the investigator
- Employees under direct or indirect supervision of the study team
- Unable to comply with all study procedures due to feasibility or logistics issues
AI-Screening
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Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Up to 12 months
Participants receive standard of care healthy diet and exercise handouts. Those in the experimental arm take extended release metformin once daily for up to 12 months, unless disease progression or unacceptable toxicity occurs. Blood samples are collected throughout the study.
Blood sample collection at baseline, 3, 6, and 12 months
Duration - Up to 12 months after treatment
Participants are followed up after treatment completion to monitor health status and study outcomes.
2 visits at 30 days and 12 months post-treatment
Trial Site Locations
Total: 3 locations
1
City of Hope Medical Center
Duarte, California, United States, 91010
Actively Recruiting
2
UC San Diego Moores Cancer Center
La Jolla, California, United States, 92093
Not Yet Recruiting
3
University of California-Riverside
Riverside, California, United States, 92521
Not Yet Recruiting
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
SUPPORTIVE_CARE
Number of Arms
2
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