Serum insulin and growth hormone in lipoatrophic diabetes

Abstract

Hypersecretion of growth hormone has been suspected as a cause of the lipoatrophy and insulin resistance in lipoatrophic diabetes. Serum insulin and growth hormone studies were performed on three siblings with lipoatrophic diabetes to obtain information regarding the role of growth hormone in this syndrome; responses to the administration of glucose tolbutamide, and insulin were investigated. The subject with only mildly abnormal glucose tolerance had serum concentrations of immunoreactive insulin which were abnormally elevated after an oral glucose load, while the two patients with more severe diabetes had normal fasting insulin concentrations which failed to increase after glucose administration. After intravenous tolbutamide, there was an abnormally slow decline in the blood sugar in all three subjects as well as a subnormal rise in serum insulin in the patient with the most severe diabetes. All patients showed resistance to insulin given intravenously but insulin antibodies were not detected in their sera. The fasting serum immunoreactive growth hormone concentration was normal (< 0.4 to 3.2 mμg./ml.) in all cases but showed little or no rise in response to hypoglycemia. Fasting plasma nonesterified fatty acid concentrations varied from 529 to 1200 μEq./L. compared to 370±20 in normal subjects and decreased after glucose administration. In these patients the serum insulin content appeared to decrease with increasing clinical severity or duration of diabetes. Increased levels of HGH were not required for maintenance of lipoatrophy or the severe insulin resistance. The relationship between failure to stimulate growth hormone secretion and the pathogenesis of lipoatrophic diabetes is unclear.