Fetal pancreatic function in infants of diabetic and rhesus-isoimmunized mothers

Objective: To measure insulin and glucagon concentrations in amniotic fluid (AF) collected near term in basal conditions and after an arginine test in diabetic, rhesus-isoimmunized, and control pregnant women. Methods: At baseline, AF was collected from 44 diabetic, 32 rhesus-isoimmunized, and 27 control pregnant women at 25-39 weeks. Fifty-two diabetic, six rhesus-isoimmunized, and nine control pregnant women had amniocentesis 2 hours after arginine infusion (30 g intravenous/30 minutes) at 33-36 weeks.Results: Baseline AF glucose concentrations were significantly greater in diabetic women than the other conditions, and they related to the gestational age in the women with hemolytic disease of the newborn. Insulin and glucagon AF content of isoimmunized pregnancies overlapped controls, whereas insulin and insulin/glucagon molar ratios were significantly higher, and glucagon values lower, in diabetic pregnancies compared with isoimmunized and control pregnancies. In isoimmunized pregnancies, the AF concentrations of glucose, insulin, and glucagon were correlated with gestational age (less than 34, 34 weeks or more). The samples collected after arginine infusion, compared with those collected at baseline, showed significantly greater insulin and insulin/glucagon molar ratio values in diabetic (28 ± 5 versus 11 ± 1 μU/mL, P = .001; 29.4 ± 1.7 versus 12.0 ± 2.8, P = .001) and in Rh pregnant women (18 ± 6 versus 7.7 ± 0.7 μU/mL, P = .001; 30 ± 9 versus 3.4 ± 0.4 I/G, P = .001), whereas no significant difference was observed in the controls.Conclusion: Basal islet hormone concentrations in AF are modified by maternal diabetes and further influenced by arginine administration. Arginine produces an AF response that is similar in pregnancies complicated by diabetes mellitus and rhesus-isoimmunization, despite different (hyperglycemia and euglycemia) maternal blood glucose levels.