The recognition that the hyperinsulinemic state is associated with the metabolic syndrome or type II diabetes mellitus is linked with increased colorectal cancer risk has led to studies of antidiabetes drugs to prevent cancer.1 Metformin has multiple actions that contribute to its potential anticancer effects,1 and has been associated with reduced cancer incidence and mortality in diabetic patients2 and patients with colorectal cancer specifically.3 In a recent double-blind, placebo-controlled, randomized phase III clinical trial in 151 patients, a low dose of 250 mg/d of metformin was associated with a decrease of approximately 40% in colorectal adenoma recurrence 1 year after initial polypectomy.