125I insulin receptor binding characteristics on umbilical cord blood erythrocytes from normal and diabetic pregnancies.

Umbilical cord blood erythrocyte insulin receptor characteristics of 13 normal and 14 diabetic pregnancies were evaluated to elucidate the effect of maternal diabetes on fetal insulin binding. Specific insulin binding to erythrocytes was similar in the two populations. However, in comparison to infants of nondiabetic women, infants of diabetic mothers exhibited a fourfold decrease in receptor affinity and a fourfold increased number of receptor sites in spite of significant hyperinsulinemia. The in utero infant of a diabetic mother therefore functions with a comparatively low affinity/high capacity insulin binding system that allows it to maintain normal insulin sensitivity in the presence of hyperinsulinemia. This altered, but balanced, mechanism may play an important role in glycemic homeostasis in utero and in the development of neonatal hypoglycemia.