The effects of aerobic exercise on glucose and counterregulatory hormone concentrations in children with type 1 diabetes

OBJECTIVE- To examine the acute glucose-lowering effects of aerobic exercise in children and adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS - Fifty children and adolescents with type 1 diabetes (ages 10 to < 18 years) were studied during exercise. The 75-min exercise session consisted of four 15-min periods of walking on a treadmill to a target heart rate of 140 bpm and three 5-min rest periods. Blood glucose and plasma glucagon, cortisol, growth hormone, and norepinephrine concentrations were measured before, during, and after exercise. RESULTS - in most subjects (83%), plasma glucose concentration dropped at least 250% from baseline, and 15(30%) subjects became hypoglycernic (<= 60 mg/dl) or were treated for low glucose either during or immediately following the exercise session. The incidence of hypoglycemia and/or treatment for low glucose varied significantly by baseline glucose, occurring in 86 vs. 13 vs. 6% of subjects with baseline values < 120, 120-180, and > 180 mg/dI, respectively (P < 0.001). Exercise-induced increases in growth hormone and norepinephrine concentrations were marginally higher in subjects whose glucose dropped 70 mg/dl. Treatment of hypoglycerma with 15 g of oral glucose resulted in only about a 20-mg/dl rise in glucose concentrations. CONCLUSIONS - in youth with type 1 diabetes, protonged moderate aerobic exercise results in a consistent reduction in plasma glucose and the frequent occurrence of hypoglycemia when preexercise glucose concentrations are < 120 mg/dl. Moreover, treatment with 15 g of oral glucose is often insufficient to reliably treat hypoglycemia during exercise in these youngsters.