[Glutamic acid decarboxylase autoantibody concentration and glucose tolerance in late pregnancy]

Genetic and immunological factors may play a role as possible causes for gestational diabetes. Autoantibodies to glutamic acid decarboxylase (GADA) are frequently found in patients with insulin dependent diabetes, but have only rarely been analyzed with regard to the carbohydrate tolerance in pregnancy. An oral glucose tolerance test (oGTT) with 75 g glucose was performed in 110 pregnant patients during the third trimenon. Glucose (glucose dehydrogenase method) and insulin (RIA) concentrations were measured after 0, 30, 60, 120, and 180 minutes. Patients were divided into five groups of increasing glucose intolerance based on the highest glucose concentration reached during the oGTT. GADA were measured using a quantitative enzyme-immunoassay. Only a single patient showed pathologically elevated GADA, and her oGTT results were within the normal range. GADA in subjects with normal pathological glucose tolerance showed no significant difference (276.6 +/- 151.6 and 263.0 +/- 107.1 mU/ml respectively). There was a tendency of positive correlations between high GADA-levels and higher concentrations of insulin as well as an increased insulin-glucose-index. These findings suggest that pregnant patients with higher GADA-levels may have an increased insulin resistance. In conclusion, the concentration of GADA was not found to be helpful in evaluating the current metabolic situation in gestational diabetes. It remains unclear whether elevated GADA during pregnancy have a prognostic value regarding the manifestation of overt diabetes mellitus later in life.