This is a double-blinded placebo controlled randomized trial examining the effect of
metformin in non-diabetic patients with colon cancer on cell growth, immunological and
metabolic changes. Patients are randomized to receive metformin 20 days before and 10 days
after surgery. Tumor samples are examined for changes in level of cell growth and the
composition of tumor cells in the tumor is examined. Blood samples are assessed for
immunological markers and insulin resistance is measured. Cell proliferation, migration and
adhesion are also examined in vitro by adding plasma obtained from the patients to colon
cancer cell lines grown in culture.