Investigation on serum C-peptide concentrations in pregnant diabetic women and in newborns of diabetic mothers

Abstract

Serum C-peptide concentrations at delivery and neonatal complications were investigated in a group of diabetic mothers and in their infants (IDM, n = 29). Furthermore, the changes in B-cell function and in daily insulin demand was followed up in 12 pregnant diabetics (of them 8 with long-term and 4 with short-term and "mild" diabetes) during pregnancy. All these diabetic mothers were under an intensive metabolic control with the aim to achieve normoglycaemia mainly in the second part of pregnancy. Mean cord blood C-peptide level of 29 IDM was 0,58 +/- 0,43 nmol/l, being not significantly higher than either the average C-peptide concentration of our adult control group (0,50 +/- 0,15 nmol/l, n = 24) or that of seven infants born to healthy mothers (0,58 +/- 0,37 nmol/l). Early hypoglycaemia was observed in five, macrosomia in three and IRDS in one neonate, resp. mothers coming to our intensive care after the 13th week of gestation gave birth with a higher incidence of neonatal complications than those controlled already in the first trimester or even preconceptionally. In 20 of 25 mothers studied venous C-peptide concentrations at delivery were undetectably low, in spite of their infants having cord blood C-peptide levels in the measurable range. In 8 of the 12 diabetic mothers with long-term diabetes C-peptide levels remained under the detection limit of the assay throughout pregnancy. In the 4 other cases with "mild" diabetes (and, hence, with a late start of intensive control) C-peptide values increased in the course of pregnancy; however, 3 of the four mothers gave birth with neonatal complications. These results indicate that (1) early--preferably preconceptional--intensive metabolic control of pregnant diabetics may reduce the incidence of neonatal complications; (2) fetal C-peptide can neither during pregnancy nor at birth pass through the placental barrier, and (3) mothers with "mild" diabetes require the same early and strict metabolic control as the more severe cases to avoid neonatal complications.