An Endometrial Cancer Chemoprevention Study of Metformin

The goal of this clinical research study is to learn about the effects of metformin and/or a program called "lifestyle intervention" on the endometrium (inner lining of the uterus) in post-menopausal women who are also obese (both are risk factors for endometrial cancer). Researchers also want to learn how insulin levels will be affected by metformin, diet and/or exercise. Metformin is designed to treat both diabetes and insulin resistance. Insulin resistance is a condition in which the body makes insulin but does not use it properly. It is often referred to as "pre-diabetes". Many people with insulin resistance have high levels of both sugar and insulin in their blood at the same time, which have been reported in patients with endometrial cancer. In this study, metformin will be compared to a placebo. A placebo is not a drug. It looks like the study drug but is not designed to treat any disease or illness. It is designed to be compared with a study drug to learn if the study drug has any real effect. Lifestyle intervention is made up of a series of in-person sessions where you meet with a coach to discuss strategies for losing weight and ways to increase physical activity. It also consists of materials designed to help you lose weight and will offer opportunities for supervised exercise.