RESUMEN
It has been appreciated for over 80 years that exercise can lower blood glucose levels in some patients with diabetes. Partly because of this, exercise has long been recommended for patients with diabetes, although its use as a therapeutic tool was never systematically examined. John Holloszy and his colleagues at Washington University were able to demonstrate that intensive physical training, 5-6 days a week for a year, could completely normalize glucose tolerance and plasma lipid abnormalities in patients with mild type 2 diabetes. Of particular note, exercise also diminished hyperinsulinaemia and insulin resistance in these patients. Studies of the effects of exercise in the therapy of type 1 diabetes revealed that the glucose lowering effect of exercise in patients with type 1 diabetes was countered by an increase in food intake, and as a result decreases in HbA1c do not occur. Since the burst of enthusiasm for the use of exercise in the therapy of type 2 diabetes in the period 1979-86, it has become increasingly apparent that exercise offers both less and more for the diabetic patient than was initially appreciated. It has also become clear that patient age, type of diabetes and presence of complications are critical factors to consider in the prescribing exercise for a given individual. Some of the major conclusions one can draw at this time are as follows: TYPE 1 DIABETES - Exercise can be an integral contributor to the quality of life of patients with type 1 diabetes just as it is in the general population. Except in the rare individual, however, it has not been a consistently useful tool for improving glycaemic control in this population. TYPE 2 DIABETES - Exercise can improve glycaemic control, diminish plasma triglycerides and insulin and improve fibrinolytic activity in patients with type 2 diabetes. It may also assist these patients in losing weight, specifically intra-abdominal fat. Exercise appears to be most beneficial in patients with glucose intolerance and mild diabetes associated with hyperinsulinaemia. To be effective, it must be performed at least 3 times a week for 30-45 minutes at 60 percent or more of the patient's maximum aerobic capacity. Exercise appears to diminish the risk of coronary heart disease in the general population. By virtue of its effects on insulin resistance and coronary risk factors, it should have an even greater effect in patients with type 2 diabetes.(Au)