Acute exercise in insulin-dependent diabetic patients may perturb glycemic control, and adjustments of insulin and diet might be required to avoid postexercise hypoglycemia. The aim of this study was to assess the role of alterations in insulin dose or caloric intake on blood glucose and free-insulin levels during 12 h after an evening bout of exercise. Nine insulin-dependent diabetic men (28–42 yr of age) receiving two daily injections with a combination of intermediate-acting and soluble insulin participated in the study. Patients were randomly assigned to four treatment protocols: A, 50% reduction in intermediate-acting insulin dose; B, 50% reduction in soluble insulin dose; C, extra caloric intake (1700 kj) 1 h after exercise; and D, no change. Exercise consisted of 45 min of cycling at 60% of maximal oxygen uptake at each occasion. Glucose and insulin responses were similar for the four protocols. There was a significant (P < .001) time effect found regardless of treatment, with lowest blood glucose values 75 min after exercise. Hypoglycemia occurred in six of the nine patients at some time during the study, with half of the occurrences on the control night (protocol D). Consistent individual plasma insulin and glucose patterns were observed independent of protocol used. In some patients, hypoglycemia was evident after reductions in insulin dose, and in others it was evident on the night increases in caloric intake were to occur; thus, none of the interventions were totally adequate in preventing exercise-induced hypoglycemia. In conclusion, general recommendations on how to adjust insulin or diet before exercise are difficult to give. Individualized recommendations for treatment modification appear most appropriate.

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