Exercise and Metformin in Colorectal and Breast Cancer Survivors

Metformin is a medication that is commonly used in the treatment of diabetes. Recently small studies in cancer patients without diabetes suggest that metformin may benefit in lowering insulin levels. In those studies of patients with cancer but not diabetes, glucose (or sugar) levels in the blood are generally no lowered. Insulin and insulin-like growth factors affect the growth of cancer cells.
This randomized study will compare different interventions; exercise, exercise and metformin, metformin alone, or a control arm. The investigators are not directly testing how either exercise or metformin affects your disease. The investigators are testing how they affect insulin levels in your body as well as other blood markers. The investigators believe that these blood tests may either be related to cancer recurrences or be an early sign of cancer recurrences and they are testing how both exercise and metformin may change those markers.