Abstract
The mechanisms underlying the beneficial effects of exercise in the treatment of diabetes are not well understood. The effect of exercise on ketone body (KB) production and utilization has also not been determined in intact man, although in severe diabetics, exercise resulted in more pronounced hyperglycemia and hyperketonemia. Six insulin-withdrawn (24 hr) insulin-dependent diabetics and 6 healthy controls were studeid at rest during and after 60 min of bicycle exercise (40% of Vo2 max). Catheter technique was employed to determine the splanchnic exchange of metabolites.
The basal arterial concentrations of glucose (258 ± 18 mg/dl), FFA (0.97 ± 0.15mmol/l) and KB (1.25 ± 0.27mmol/l) were significantly higher in the diabetic patients than in the controls. The arterial FFA level remained unchanged or increased slightly during exercise, rose distinctly 5-20 min after exercise and then decreased gradually. The concentration changes occurred in parallel for the two groups but the levels were 60-100% higher in the diabetics. The patients' basal splanchnic ketone production (SKP)(0.72 ± 0.07mmol/min) rost to 0.96 ± 0.17mmol/min during exericse and increased further to 1.18 ± 0.15mmol/min at 20 min after exercise. It remained unchanged or even increased for 60 min after exercise. The arterial KB levels were unchanged during exercise but rose to 2.02 ± 0.28mmol/l at 20 min after exercise in the diabetics. In contrast, the SKP in controls was 0.09 ± 0.02mmoles/min at rest, rose 3-fold during exercise, peaked at 10-20 min after exercise and then decreased gradually. It is concluded that the stimulation of KB production during exercise persisted during the post-exercise recovery period in the diabetics but not in the controls, probably as a result of insulin deficiency in the diabetics. These findings emphasize the importance of adequate insulin therapy in connection with exercise.
