Eight insulin-dependent adolescents (4 boys, 4 girls) participated in an 8-wk program of supervised exercise, and 8 matched controls were encouraged to exercise on their own without supervision. All 16 subjects were asked to follow a standard ADA diet plan, kept a self-reported log of caloric intake, and met with a dietitian weekly to review their diets. Exercise for the supervised subjects was scheduled between the routine afternoon snack and the evening meal, and subjects were asked not to consume additional food on exercise days. After the 8-wk program, glycemic control, as measured by glycosylated serum albumin and blood glucose values (but not by glycosylated hemoglobin), improved in the supervised-exercise group despite reduced daily insulin dosage. Cardiorespiratory fitness, as measured by voluntary maximum treadmill time (Bruce protocol) and submaximal exercise heart rates, also improved. No changes were observed in the unsupervised control group.

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In brief: The acute effect of exercise on blood glucose was observed on 130 occasions in eight adolescents with insulin-dependent diabetes mellitus. All subjects engaged in 30 minutes of either structured aerobic exercise or unstructured recreational activity. The magnitude of decline in the blood glucose level with exercise corresponded to the preexercise blood glucose value: Higher preexercise values were associated with larger declines, while nonelevated preexercise values were associated with smaller declines. No significant differences in glycemic effect were observed between the two categories of exercise. The authors conclude that in adolescents with moderately well-controlled diabetes, recreational activities can be as effective in lowering elevated blood glucose levels as structured exercise.