The prevalence of type 2 diabetes mellitus is rapidly increasing, and with it the risk for cardiovascular events. Diabetic patients with cardiovascular disease have a very unfavourable prognosis and their management remains a challenge, despite recent progress with angiotensin-converting enzyme inhibitors and statins. Metabolic factors associated with diabetic status are of critical importance, both for the myocardium and for the vascular system in general. An important effect of diabetes that impacts on cardiac function is the switch from carbohydrate to free fatty acid oxidation. Correction of the alterations in cardiac metabolism associated with diabetes may represent a new approach to the management of ischaemic heart disease. Results obtained with trimetazidine and ranolazine in patients with angina pectoris are consistent with this hypothesis. Evidence for the beneficial effects of meticulous insulin-based glycaemic control in patients with acute myocardial infarction also suggests an important role for metabolic therapy. More knowledge on the metabolism of diabetic patients, and active collaboration between endocrinologists and cardiologists are essential if we are to achieve further success in managing diabetic patients who are at risk for cardiovascular disease. The present reviews addresses current information on the metabolism of the diabetic heart.