Comparison of Cord Blood Viscosity and C-Peptide Levels in Infants of Diabetic Mothers (IDM), Macrosomic Infants (LGA) and Normal-Sized Neonates (NC)

Abstract 1542 Mean plasma levels of C-peptide protein in cord blood have been shown to be higher in LGA infants than in AGA term infants, and it has been suggested that chronic fetal hyperinsulinemia may be one cause of macrosomia in infants of non-diabetic mothers. In a previous study, we had observed that in blood samples taken during the first to third postnatal day, blood viscosity at specific hematocrit levels above 57% was higher in LGA plus IDM infants than in NC infants. We hypothesized a possible correlation between whole blood viscosity and plasma C-peptide levels in cord blood. We therefore compared mean viscosity at a standardized hct of 50%, and at selected shear rates, in cord blood from groups of LGA, IDM and NC infants, and also evaluated a possible correlation between viscosity and C-peptide levels in all the infants, as well as in infants within each of the respective groups. (Table) No significant differences in mean viscosity values were observed among the 3 groups ("t" test); nor was there any significant correlation between C-peptide concentration and viscosity within each group or in the whole infant sample (Pearson test). However, mean C-peptide concentration in the LGA group was significantly higher than in the NC group (p = 0.006) and also higher than in the IDM group (p = 0.013). (ANCOVA, adjusting for multiple comparisons.) There was no significant difference between IDM and NC groups. Within each group infant weight did not contribute toward differences. We speculate that some of the LGA infants could have been exposed to subtle maternal hyperglycemia during gestation, and as a group are therefore at greater risk for neonatal hypoglycemia than infants of well-controlled diabetic or gestational diabetic mothers.