Heart failure affects nearly 5 million people in the United States and is a major contributor to mortality, hospitalization, and medical costs. Approximately 40% of patients with heart failure have preserved left ventricular systolic function, thus exhibiting diastolic heart failure. More common in women and the elderly, this condition is associated with hypertension, coronary artery disease, and/or atrial fibrillation. With the exception of the Digitalis Investigation Group (DIG) and the Candesartin in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM)-Preserved trials, no completed large randomized clinical trial has addressed the management of such patients. Symptomatic treatment involves administration of diuretics and nitrates, but long-term management with angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, aldosterone antagonists, beta-blockers, and calcium channel blockers targets the underlying disorders. Recent studies found that diabetes mellitus produces functional, biochemical, and morphologic myocardial abnormalities independent of coronary atherosclerosis and hypertension. These abnormalities may result in impaired left ventricular diastolic function, contributing importantly to heart failure with normal systolic function. Although tight glycemic control decreases the risk of heart failure in patients with diabetes, the effects of different diabetic treatment regimens on heart failure with normal systolic function are unknown and remain subject to future investigation.