Postprandial exercise in type I diabetic patients on multiple daily insulin injection regimen

This study shows the influence on plasma glucose concentrations of 45 min of mild exercise (48 +/- 4% of maximum aerobic capacity) performed 180 min after breakfast and 195 min after a subcutaneous injection of regular insulin by six type I (insulin-dependent) diabetic patients on a three-daily insulin injection regimen (regular insulin before breakfast and lunch, regular + intermediate insulin before supper). It has been observed that such exercise does not induce a large plasma glucose decrease. Actually, plasma glucose concentrations were 99 +/- 18 mg/dl before exercise, reached a nadir of 78 +/- 17 mg/dl at 35 min, and were 81 +/- 15 mg/dl at the end of exercise. During the control study at rest, in the same 45-min time interval, plasma glucose decreased from 146 +/- 31 to 128 +/- 31 mg/dl. In the exercise study, one patient began exercising while hypoglycemic, and another patient developed asymptomatic hypoglycemia during exercise. In the control study at rest, one patient showed hypoglycemic glucose concentrations. Throughout the exercise study, plasma free-insulin concentrations decreased (from 32 +/- 5 to 20 +/- 4 microU/ml) as a result of the pharmacokinetics of subcutaneously injected insulin.