INSULIN-RESISTANCE IN LIMB AND TRUNK PARTIAL LIPODYSTROPHY (TYPE-2 KOBBERLING-DUNNIGAN SYNDROME)

We studied insulin action in two patients with limb and trunk partial lipodystrophy with hirsutism and acanthosis nigricans. Glucose was nor mal in one of the patients and slightly above normal in the other duri ng an oral glucose tolerance test (OGTT). An intravenous glucose toler ance test (IVGTT) was normal in both patients. Basal and glucose-stimu lated insulin levels were elevated in both the OGTT and IVGTT in both patients. The response of plasma glucose to exogenously administered i nsulin was decreased. A euglycemic-hyperinsulinemic clamp performed in patient no. 2 indicated insulin resistance, which was not corrected b y reducing the increased basal level of serum free fatty acids (FFAs). Binding of insulin to neck adipocytes was normal in both subjects, bu t glucose transport and oxidation in these cells was impaired. Insulin binding to abdominal adipocytes was increased in one patient whose ad ipocytes displayed higher glucose transport at low insulin concentrati ons. Glucose oxidation was decreased in abdominal adipocytes of both p atients. We conclude that insulin resistance in Kobberling-Dunnigan ty pe 2 partial lipodystrophy is not related to an alteration of the insu lin molecule or to changes in insulin binding, but is more likely asso ciated with a postreceptor defect, since glucose oxidation was impaire d in adipocytes of the neck and abdomen. Copyright (C) 1997 by W.B. Sa unders Company.