OBJECTIVE To analyze the association among impaired glucose tolerance (IGT), diabetes, and cardiovascular disease (CVD). METHODS We review current studies that have addressed the foregoing relationship and summarize the results of diagnostic and therapeutic interventions. RESULTS A major cause of the reduction in life expectancy in patients with diabetes is CVD and cardiovascular complications. Both prediabetes and diabetes predispose to cardiovascular alterations. IGT and even the upper normal values of nondiabetic glucose levels are associated with an increased cardiovascular risk. The risk of heart disease can be increased as early as 15 years before the diagnosis of diabetes. Patients with chronic or acute CVD and no previous diagnosis of diabetes frequently present with either IGT or diabetes. Thus, such patients should undergo screening for diabetes with an oral glucose tolerance test. In acute coronary syndromes, lowering of glucose levels to the near-normal range by administration of insulin is highly beneficial. Early, rigorous interventions to improve metabolic control will yield better cardiovascular outcomes in patients with dysglycemia. CONCLUSIONS Aggressive preventive and treatment strategies, which can include multiple interventions, are needed to minimize the potential effects of CVD in patients with diabetes or IGT.