Abstract
We aimed to evaluate gestational impaired glucose tolerance (GIGT) in untreated patients using umbilical cord blood insulin and connecting peptide (C-peptide) concentrations to indicate fetal hyperinsulinemia. A 75 g, 2-hour oral glucose tolerance test, evaluated using WHO criteria, was performed in 722 antenatal patients. Cord C-peptide (p = 0.001) and insulin (p = 0.008) concentrations were significantly higher in patients with GIGT in comparison to those with normal glucose tolerance. The WHO test failed to identify abnormal C-peptide concentrations (p = 0.057), but did identify abnormal insulin concentrations (p = 0.006) and cases where either or both were raised (p = 0.002), with a low Youden’s index (range 8.1–11.3) in all 3 cases. A significant biochemical difference exists in patients with GIGT. The WHO criteria for GIGT predict abnormal biochemical outcomes, but they do so poorly.