Insulin action in adipose tissue in type 1 diabetes

Background: Insulin action has been reported to be normal in type 1 diabetic patients. However, some studies have reported an insulin resistance state in these patients. The aim of this study was to investigate insulin resistance in a group of type 1 diabetic patients. We studied the insulin action in adipose tissue and analyzed the effects of duration of disease, body mass index (BMI), and glycosylated hemoglobin on insulin action at the receptor and postreceptor levels in adipocytes. Methods: Nine female type 1 diabetic patients with different durations of disease and eight nondiabetic female patients of comparable age and BMI were studied. 125I-insulin binding and U-[14C]-D-glucose transport was measured in a sample of subcutaneous gluteus adipose tissue obtained by open surgical biopsy from each subject. Results: The duration of disease was negatively correlated with both 125I-insulin binding capacity (r = -0.70, P < 0.05) and basal and maximum insulin-stimulated glucose transport (r = -0.87, P< 0.01, and r = -0.88, P < 0.01, respectively). Maximum specific 125I-insulin binding to the receptors in adipocytes was higher in the group of patients with a shorter duration of disease (P < 0.01). Basal and maximum insulin-stimulated glucose transport was significantly higher in the group with less than 5 years of disease (P < 0.01). No correlation was found between BMI and insulin action. Conclusion: Female type 1 diabetic patients have normal insulin action. There is a high glucose uptake in the early phase of the disease, although a longer duration of disease appears to be a contributing factor to a decrease in insulin action in these patients, and involving both receptor and postreceptor mechanisms.