Insulin levels in the umbilical vein and in the umbilical artery of newborns of normal and gestational diabetic mothers.

Abstract

Insulin levels (by double antibody radioimmunological assay) were studied in the venous blood of mothers at vaginal delivery and in the umbilical vein and artery of their newborns. — In 14 normal mothers the insulin levels after 10 hours fasting were 18.5±3.6 μU/ml (mean±S.E.M.). In their newborns (mean: 3.420 kg, all < 4.000 kg, 38–41 weeks gestation) the insulin levels were low and similar in the umbilical vein (5.6±0.7 μU/ml) and in the umbilical artery (6.6±0.7 μU/ml). The plasma glucose levels in the mothers were 99.7±3.9 mg/100 ml and in the umbilical vein 77.3±3.7 mg/100 ml and the umbilical artery 65.5±3.2 mg/100 ml. They were significantly different from each other. — Eleven normal mothers receiving a glucose infusion (ca. 15 g/3 hours) during delivery had 42.0±9.9 μU/ml insulin in their venous blood. In their newborns with a normal birth-weight (mean: 3.585 kg, all < 4.000 kg) the insulin levels were not increased either in the umbilical vein (7.0±1.0 μU/ml) or in the artery (7.9±1.0 μU/ml). The plasma glucose levels in the mothers were 128.0±7.7 mg/100 ml, and in the umbilical vein 105.0±7.5 mg/ 100 ml and in the umbilical artery 88.8±8.6 mg/100 ml. The plasma glucose levels were significantly different from each other. — In six infants with “large birthweight” (> 4.100 kg) born to untreated mothers with gestational diabetes the insulin levels were superior to the values found in normal newborns. In three of these infants, born to mothers who did not receive a glucose infusion, the insulin levels in the umbilical vein were 38, 42 and 13 μU/ml, and in the artery they were 17, 34.5 and 18.5 μU/ml. The other three mothers received a glucose infusion, their newborns had in the umbilical vein an insulin level of 15.5, 65 and 19 μU/ml and in the artery 20, 72.5 and 14 μU/ml. — In conclusion, the normal infant at birth has a low insulin level, which is equal in the umbilical vein and artery. In 6 heavy infants born to untreated latent diabetic mothers, the insulin levels were significantly higher than in normals, and the levels in the umbilical vein and the artery were different from one another. This latter data on hyperinsulinism is discussed in relation with hyperplasia of the islets of Langerhans observed in stillborn infants of mothers with insulin-dependant diabetes or gestational diabetes.