HORMONAL ENTEROINSULAR AXIS IN NEWBORN-INFANTS OF INSULIN-TREATED DIABETIC MOTHERS

To study whether the increased glucose levels in the amniotic fluid du ring diabetic pregnancies induce an early maturation of the hormonal e nteroinsular axis, we measured blood glucose levels and plasma concent rations of C-peptide, pancreatic glucagon, enteroglucagon, and gastric inhibitory polypeptide (GIP) in cord blood from 18 newborn infants of insulin-treated diabetic mothers (IDM) and 18 infants of nondiabetic mothers. In addition, we studied the same parameters in 20 IDM and 12 control infants before and after their first feed comprising human mil k (5 mL/kg), given by nasogastric tube at the age of 2 h. The IDM had significantly higher blood glucose levels and plasma C-peptide concent rations in their cord blood than the control infants, which was follow ed postnatally by a substantial fall in these levels, whereas a more m odest decrease could be seen in the control infants. Circulating enter oglucagon and GIP concentrations at the age of 2 h were significantly higher than those observed in cord blood in both the IDM and the contr ol infants, but the IDM had significantly lower blood glucose levels, higher plasma C-peptide, and lower enteroglucagon concentrations befor e the first feed. There was a significant increase in blood glucose le vels after the feed in both the IDM and the control infants, and the c oncentrations 2 h after feeding were of the same magnitude in the two groups. No significant C-peptide response could be observed in either group, but the IDM continuously had higher C-peptide concentrations. A significant enteroglucagon and CIP response could be seen in the IDM, whereas the controls exhibited only a GIP response. However, no signi ficant differences were found between the two groups in the absolute p ostprandial plasma concentrations of these hormones. Our results show rapid, substantial postnatal changes in circulating concentrations of enteroinsular hormones in both IDM and control infants. Enteral feedin g with human milk corrects early postnatal hypoglycemia within 2 h in most IDM without causing any exacerbation of their hyperinsulinemia. T he absence of any C-peptide response to the first feed and of any obse rved differences between IDM and normal infants in absolute concentrat ions of enteroglucagon and GIP after the first feed suggests that the enteroinsular axis matures postnatally in both groups of infants.