Abstract
C-peptide responses to glucose were investigated in full term fetuses at the time of delivery. Glucose was administered continuously by drip infusion to the mothers during labour. Plasma glucose of the umbilical artery and vein rose immediately during a glucose load, whereas plasma IRI and C-peptide of these vessels were not elevated during first 40 minutes of the glucose load. Significant elevation of plasma IRI and C-peptide was demonstrated only after 44 minutes or longer. It was also demonstrated that placental transfer of C-peptide is extremely limited, as no significant correlation between the levels of umbilical arterio-venous difference and maternal vein levels was found. Blood samples of these fetuses were also obtained by heel stab 30 minutes after birth. IRI levels were significantly lower during this period, while C-peptide levels were elevated.
IRI and C-peptide responses in newbornes and older infants were examined by administering milk (15 ml per kg body weight). Their responses varied quite widely and seemed not to be dependent on the age of newborn. Relatively high C-peptide levels were found in 1-4 day-old infants. These findings may be partly due to immaturity of renal function during this postnatal period.
