Human Fetal Insulin Response to Sustained Maternal Hyperglycemia

Abstract

Hyperglycemia was maintained in normal mothers before delivery both at term and early in gestation to study the fetal pancreatic response to glucose. Normal controls and gestationally diabetic mothers were infused with saline. At term the human fetal pancreas responded to elevated blood glucose levels by increasing plasma insulin, and there was a direct correlation between blood glucose and plasma insulin concentrations (r equal to 0.75, p less than 0.001). In early gestation there was an attenuated plasma insulin response. Infants of gestationally diabetic mothers had increased umbilical plasma insulin levels — 23.3 ± 6.9 μU per milliliter (mean ± S.E.M.) — as compared to those of normal controls - 6.4 ± 1.3 μU per milliliter (mean ± S.E.M.) — even though the umbilical blood glucose levels in these two groups were similar. The data support the concept that hyperglycemia leads to hyperinsulinism in infants of diabetic mothers.