Increased insulin receptors after exercise in patients with insulin-dependent diabetes mellitus

Physical exercise is known to improve glucose tolerance and diminish insulin requirements in patients with well-controlled diabetes mellitus. To ascertain whether these effects of exercise are associated with alterations in insulin receptors, we studied [125I]insulin binding to erythrocytes and monocytes in athletically untrained young men with insulin-treated diabetes during three hours of postprandial bicycle exercise (nine patients) and two hours of exercise during fasting (eight patients). Compared with control periods, postprandial exercise, as well as exercise during fasting, significantly increased insulin binding to erythrocytes and monocytes at an insulin-tracer concentration of 34 pmol per liter. We suggest that similar changes occur in working muscle cells and contribute to the improved glucose tolerance induced by exercise.