Effects of exercise on the absorption of insulin glargine in patients with type 1 diabetes.

OBJECTIVE To study the effects of exercise on the absorption of the basal long-acting insulin analog insulin glargine (Lantus), administered subcutaneously in individuals with type 1 diabetes. RESEARCH DESIGN AND METHODS A total of 13 patients (12 men, 1 woman) with type 1 diabetes on a basal-bolus insulin regimen were studied. (125)I-labeled insulin glargine at the usual basal insulin dose was injected subcutaneously into the thigh on the evening (2100) before the study day on two occasions 1 week apart. Patients were randomly assigned to 30 min intense exercise (65% peak oxygen uptake [Vo(2peak)]) on one of these visits. The decay of radioactive insulin glargine was compared on the two occasions using a thallium-activated Nal gamma counter. Blood samples were collected at regular intervals on the study days to assess plasma glucose and insulin profiles. RESULTS No significant difference was found in the (125)I-labeled insulin glargine decay rate on the two occasions (exercise vs. no exercise; repeated-measures ANOVA, P = 0.548). As expected, a significant fall in plasma glucose was observed over the exercise period (area under curve above fasting [DeltaAUC] glucose: -0.39 +/- 0.11 vs. -1.30 +/- 0.16 mmol . l(-1) . h(-1); nonexercise vs. exercise; P = 0.001), but insulin levels did not differ significantly on the two occasions (DeltaAUC insulin: -2.1 +/- 3.9 vs. 1.5 +/- 6.2 pmol . l(-1) . h(-1); nonexercise versus exercise; P = 0.507). CONCLUSIONS An intense 30-min period of exercise does not increase the absorption rate of the subcutaneously injected basal long-acting insulin analog insulin glargine in patients with type 1 diabetes.