The major metabolic substrates of the normal well-oxygenated myocardium are free fatty acids in the fasted state and glucose in the fed state. In general, the normal myocardium uses whichever fuel is available. During ischemia, there is a swing toward glucose metabolism and it is proposed that glycolysis provides beneficial glycolytic ATP which has many protective actions, including preservation of sodium pump activity. Hypothetically, when sodium pump activity stops, cytosolic calcium increases and ischemic contracture, often an irreversible event, occurs. The rise in internal sodium may alter sodium/calcium exchange, thus precipitating contracture. In the postischemic myocardium, glycolysis is again essential, but there is increasing evidence that citric acid cycle intermediates need to be replenished by anaplerosis. In diabetic patients, glucose-insulin-potassium (GIK) infusions, followed by subcutaneous insulin, have been shown to reduce mortality over the year following the onset of acute myocardial infarction...