Neonatal 24-hour urinary C-peptide and birth weight in infants of diabetic mothers.

Abstract

Our purpose was to investigate the relationship between the birth weights and 24-h urinary C-peptide in infants of diabetic mothers. Sixty pregnancies with gestational diabetes mellitus (DM) were enrolled. Neonatal urine was collected for the first and second 24 h for measuring C-peptide. Birth weights were classified into 3 categories according to the Japanese standard curves; heavy-for-date (HFD), appropriate-for-date (AFD), and light-for-date (LFD). Unpaired t-test was used for comparison of 24-h urinary C-peptide in the 3 birth weight categories, with P-value <0.05. There were 7 HFD, 47 AFD, and 6 LFD infants. Birth weight averaged 3.9+/-0.7, 3.0+/-0.4, and 2.3+/-0.3 kg, respectively. Insulin concentrations of the umbilical artery were significantly higher in HFD than in AFD, and significantly higher in AFD than in LFD (49.5+/-45.1, 16.8+/-15.2, and 6.3+/-6.1 microU/ml). During the first 24 h, urinary C-peptide was significantly higher in HFD than in AFD (2.73+/-1.52 vs. 0.76+/-0.81 microg/day), and significantly higher in AFD than in LFD (0.27+/-0.27). On the second day, there was no longer statistical significance. Measurement of 24-h urinary C-peptide revealed that, among infants of diabetic mothers, HFD infants continue to secrete more insulin than AFD and LFD infants for the first 24 h.