[Postpartum diagnosis of diabetes in pregnancy in fetal macrosomia--comparison of two examinations].

Disorders of carbohydrate metabolism in pregnancy are often associated with macrosome newborns. There are two methods with different approach for retrospective diagnosis of gestational diabetes (GDM): 1. maternal postnatal oral glucose tolerance test (ppoGTT), 2. determination of cord blood insulin for detection of fetal hyperinsulinism. The presented study deals with the question how often macrosomia is correlated with pathologic cord blood insulin respectively pathologic ppoGTT and if both methods select identical collectives. Cord blood insulin was determined by RIA in 154 newborns with birth weight over the 90th percentile (threshold 15 microU/ml). On the 2nd day p.p. oGTT was performed in 80 women without prenatal diagnosis of GDM (threshold 95, 165, 145, 125 mg%). 37/154 (24%) newborns showed pathologic insulin values. 24/80 (30%) women had pathologic ppoGTT. In 30% of the cases pathologic results of cord blood insulin and ppoGTT selected different collectives: 17/66 pathologic ppoGTT with normal insulin values, 7/14 normal ppoGTT with pathologic insulin values. The only use of ppoGTT would fail in 50% of cases of GDM with proved fetal hyperinsulinism. The determination of cord blood insulin offers the opportunity of direct diagnostics on the child in contrast to maternal ppoGTT. For retrospective diagnosis of macrosomia due to disorders of carbohydrate metabolism determination of cord blood insulin should be given preference to oGTT in puerperium.