Isolated polyhydramnios in the third trimester: is a gestational diabetes evaluation of value?

We evaluated implications of testing for gestational diabetes mellitus (GDM) in pregnancies complicated by third trimester isolated polyhydramnios with previous negative diabetes screening test. In this retrospective cohort study of 104 pregnant women with polyhydramnios between 2005 and 2013, all had normal first trimester fasting glucose and normal glucose challenge test (GCT < 140 mg/dL). Late onset GDM was diagnosed in five women (4.8%) with isolated polyhydramnios, one abnormal value in the oral glucose tolerance test (OGTT) was identified in four additional women (3.8%). No significant differences were found in risk factors for GDM, mean second trimester GCT (117.5 vs. 107.2 mg/dL, p = 0.38) or fasting glucose values (82 vs. 86 mg/dL, p = 0.29) between women in the polyhydramnios group with and without late GDM diagnosis. Moreover, no significant difference was found in relation to the mode of delivery or birth weight between the studied groups (3437 ± 611 vs. 3331 ± 515 g, p = 0.63). Diagnosis of third trimester polyhydramnios was not associated with increased risk for GDM or neonatal complications.