Influence of the Maternal Plasma Glucose Concentration at Delivery on the Risk of Hypoglycaemia in Infants of Insulin-Dependent Diabetic Mothers

Plasma glucose concentrations at birth and at two hours of age were measured in 53 infants of insulin-dependent mothers (IDMs). The plasma glucose concentrations at delivery were measured in the mothers of 17 IDMs and in the remaining 36 mothers, glucose was estimated by interpolation from concentrations achieved just before and after delivery. Clinical and laboratory data from the two groups were otherwise similar, so the groups were combined for further analyses. The maternal plasma glucose at delivery correlated positively with the glucose concentration of the IDMs at birth (Q=0.82, p <0.001) and negatively with the glucose concentration at two hours of age (Q= -0.46, p <0.001). Maternal plasma glucose concentration was higher in mothers delivered by caesarean section than in vaginally delivered mothers ( p <0.05). Eleven IDMs became hypoglycaemic at two hours of life (plasma glucose ≥1.7 mmol/1). These infants had higher cord plasma glucose concentrations at birth than those who remained normoglycaemic; the maternal glucose concentration was also higher. None of the IDMs became hypoglycaemic if the maternal glucose concentration at delivery was less than 7.1 mmol/l. In 28 IDMs the simultaneous plasma concentrations of non-antibodybound immunoreactive insulin (IRI) were recorded. Cord plasma IRI correlated with glucose and IRI at two hours of age (Q=-0.73, p <0.001 and Q=0.77, p <0.001, respectively). Cord plasma IRI was higher in IDMs who became hypoglycaemic than in the remaining infants. The results suggest that among the factors which may be responsible for neonatal hypoglycaemia in IDMs a major factor may be the maternal plasma glucose concentration at the time of delivery.