In vivo and in vitro characterization of insulin resistance in three cases of lipoatrophic diabetes.

Insulin resistance was explored in vivo and in vitro in 3 lipoatrophic diabetic girls (12, 15 and 19 years old = L1, L2 and L3). Patients L1 and L2 were explored with fasting hyperglycaemia (9 mmol/l); patient L3 was normoglycaemic. All had abnormal OGTT with marked hyperinsulinemia. Their basal glucose productions, measured by [6,6(-2)H] glucose constant infusion, were 3.3, 2.6 and 3.4 mg kg-1 min-1, respectively; they did not correlate with fasting plasma glucose. Glucose production in response to a 2 mg kg-1 min- unlabeled glucose infusion, was normally suppressed in L2, but was incompletely suppressed (by 1.5 mg kg-1 min-1) in L1 and L3. The dose-response curve during hyperinsulinemic euglycaemic clamp at 1, 2 and 10 mU kg-1 min-1 insulin infusion was shifted to the right in all three patients. However the maximal glucose disposal rates were close to normal (9 and 9 mg kg-1 min-1) in L1 and L3, while it remained very low (3.6 mg kg-1 min-1 at 10 mU kg-1 min-1 insulin infusion) in L2. The endogenous insulin secretion (plasma C-peptide) was also incompletely suppressed during insulin infusion. Thus, the in vivo insulin resistance of lipoatrophic diabetes concerns not only glucose disposal but also hepatic glucose output and insulin secretion; in addition, the alterations of glucose metabolism were not the same in all subjects. The in vitro studies showed no pre-receptor defect (anti-insulin antibodies, insulin receptor antibodies). Insulin binding to erythrocytes and cultured fibroblasts was normal.(ABSTRACT TRUNCATED AT 250 WORDS)