Diabetes is a strong and independent risk factor for the development of heart failure, and once heart failure occurs, patients with diabetes have a much poorer prognosis than do those without diabetes. This difference has been explained by the existence of a distinct diabetic cardiomyopathy characterized by morphologic and structural changes to the myocardium and coronary vasculature. Despite diabetic cardiomyopathy, the pharmacologic treatment of heart failure in diabetic patients is similar to that in patients without diabetes, and in general, the clinical response of diabetic patients to drug therapies for heart failure is similar, if not superior, to that of nondiabetic patients. Subgroup analyses from large clinical studies have shown that angiotensin-converting enzyme inhibitors not only reduce mortality in diabetic patients with heart failure, but also reduce the incidence of heart failure in at-risk diabetic patients. β-Blockers remain underused in the diabetic population despite overwhelming evidence of their efficacy in treating heart failure in patients with diabetes.