Diabetes mellitus (DM) imposes an approximate 2-fold increased risk of atherothrombosis. Patients with type 2 DM have a 2- to 4-fold increase in the risk of coronary artery disease (CAD) and atherothrombotic complications. Current evidence indicates that altered platelet function and "reactivity" are key determinants of arterial and venous thrombosis in metabolic syndromes. In addition, venous thrombosis and pulmonary embolism are associated with increased body mass index, a common feature of type 2 DM and the metabolic syndrome. Altered platelet behavior, function, and phenotype may be critical factors in these thrombotic complications as well. The mechanisms that lead to altered phenotype and function of platelets in DM, and that underlie heightened contributions of platelets to thrombotic complications in type 2 DM, are nevertheless incompletely understood. In this project, the investigators will prospectively determine if clinical intervention with metformin--a commonly-used therapeutic agent that reduces blood glucose, promotes weight loss, and improves lipid profiles--reverses platelet reprogramming and hyperreactivity in obese subjects with impaired fasting glucose and thus, at-risk for type 2 DM.