Oral glucose tolerance test for suspected late onset gestational diabetes

Background: Oral glucose tolerance test is used for the diagnosis of gestational diabetes at the second trimester, however, its use at term has been questioned. Objective: To compare obstetric outcomes in women with and without abnormal oral glucose tolerance test (OGTT) conducted at term due to large for gestational age (LGA) fetuses or polyhydramnios. Methods: A retrospective cohort study including all women >= 37 weeks of gestation, with normal glucose challenge test (GCT), who performed 100 g OGTT at term, due to LGA fetus or polyhydramnios between January 2012 and January 2017. Abnormal OGTT was considered according to Carpenter and Coustan criteria. Data are presented as median and inter-quadrantile range (IQR). Results: Database included 34,897 women, of them, 1131 (3.2%) met inclusion criteria. A total of 150 (13.2%) and 981 (86.7%) women were included in the abnormal and the normal OGTT groups, respectively. Women in the abnormal OGTT group had higher glucose levels on GCT [126 (IQR 107-137) versus 110 (IQR 91-132) mg/dL; p = .001]. The rate of cesarean deliveries was twice as high in the abnormal OGTT group [37 (24.7%) versus 103 (10.5%); p = .001]. No difference in the rate of shoulder dystocia, postpartum hemorrhage (PPH) or third and fourth-degree perineal tear was observed among women who delivered vaginally. Conclusions: Abnormal OGTT at term was related to a higher rate of cesarean deliveries, with no difference in obstetrical complications among women who delivered vaginally.