This review discusses the current data on various antidiabetic medications and their effects on major adverse cardiovascular events (MACE). Diabetes mellitus is a potent independent risk factor for MACE, and this risk increases in proportion to the elevation of hemoglobin A^1c. Available data suggest that tight glycemic control in patients with diabetes reduces microvascular complications, but has limited effect or may even increase the risk of MACE and other macrovascular complications. For individuals with type 2 diabetes mellitus (T2DM) drugs that reduce postprandial glucose (α-glucosidase inhibitors, incretin mimetics, quick-acting bromocriptine, dipeptidyl peptidase-4 inhibitors, and colesevelam) are associated with a decrease in MACE. Drugs that directly reduce insulin resistance (pioglitazone and metformin) are also associated with lesser but still significant decreases in MACE. Insulin, rosiglitazone (but not pioglitazone), and sulfonylureas (especially with glyburide and particularly the glyburide + metformin combination) are associated with increases in MACE. In summary, drugs that reduce postprandial glucose and improve insulin resistance without predisposing patients to hypoglycemia appear to both control hyperglycemia and improve cardiovascular prognosis. However, many of the traditional agents used for treating T2DM, such as insulin and sulfonylureas, do not improve cardiovascular prognosis despite improving hyperglycemia.