Evaluation of oral glucose tolerance test, β-cell function and adverse obstetric outcomes

This study was conducted in order to investigate the prevalence of impaired glucose tolerance (IGT) and gestational diabetes mellitus (GDM), their effect on pregnancy and their association with adverse obstetric outcomes. A cross-sectional study was performed on 345 pregnant women, who were screened between the 24th and 28th gestational week with a 75-g oral glucose tolerance test following abnormal results at 1 h after a 50-g oral glucose challenge test. The obstetric outcomes were recorded along with plasma glucose and insulin levels, homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β-cell function index (HOMA-βCFI) and 50 subjects were excluded due to incomplete data recovery. Of the 295 pregnant women, 18.6% (55/295) were diagnosed with GDM and 32% (95/295) with IGT. The GDM group exhibited significantly higher fasting and 1-h blood glucose concentrations compared to the normal glucose tolerance (NGT) and IGT groups (P<0.01). The 2- and 3-h insulin values of the NGT group were significantly lower compared to those of the GDM group (P<0.05, P<0.01). In the IGT group, the 2-h insulin values were higher compared to the NGT group and the 3-h values were significantly higher (P<0.01), similar to the GDM group. There was a tendency for progressively decreased β-cell function and increased HOMA-IR from the NGT to the IGT to the GDM group. The adverse outcomes of pregnancy-induced hypertension, fetal distress, neonatal hyperbilirubinemia, preterm delivery, macrosomia and cesarean delivery indicated an association with HOMA-βCFI and HOMA-IR. In conclusion, these findings suggest a clinical significance of β-cell dysfunction in women with gestational IGT.