Background: Understanding how C-peptide levels in the umbilical cord can be used to predict when a diabetic mother's newborn will experience hypoglycemia is urgently needed. This study aimed to assess the role of umbilical cord C-peptide levels in the early prediction of hypoglycemia among neonates of diabetic mothers.

Methods: We carried out this cross-sectional study on 52 singleton newborns born to diabetic mothers in the neonatal resuscitation room and obstetric operation room at Zagazig University Hospital. The umbilical cord C-peptide concentration was assessed via an enzyme-linked immunosorbent assay. complete blood count, blood glucose level, insulin level, and glycated hemoglobin (HbA1C), were performed for neonates and mothers. Neonatal blood glucose was measured hourly three times.

Results: A significant association was found between neonatal C-peptide levels and maternal premature rupture of membranes (p=0.013). Compared to normoglycemic neonates, hypoglycemic neonates had significantly higher C peptide levels (p<0.001). The best cut-off value of neonatal C-peptide for the prediction of neonatal hypoglycemia is ≥0.3685 ng/ml, with an area under the curve of 0.963, a sensitivity of 88.9%, a specificity of 88.4%, a positive predictive value of 61.5%, a negative predictive value of 97.4%, and accuracy of 88.5% (p<0.001).

Conclusion: This study underscores the importance of monitoring umbilical cord C-peptide levels as a potential early predictor of neonatal hypoglycemia among infants born to diabetic mothers.