736 Comparing neonatal outcomes among patients undergoing intravenous glucose tolerance testing for diagnosis of gestational diabetes

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To assess neonatal outcomes associated with abnormal intravenous glucose tolerance test (IV GTT) results in a cohort of patients unable to tolerate the standard oral glucose tolerance test for diagnosis of gestational diabetes (GDM). Patients who could not tolerate an oral glucose load, were > 24 weeks gestation, had a viable singleton or multifetal gestation, and spoke English or Spanish were enrolled prospectively between February 2019 and February 2020. Patients with pre-existing diabetes mellitus (DM) or clinically significant hemoglobinopathies were excluded. Enrolled patients underwent an IV GTT and glucose monitoring was initiated if the IV GTT resulted in a glucose metabolism rate below trimester-specific normative values. The primary outcome of interest was large for gestational age (LGA) infants. The study was powered to detect a 25% difference in LGA infants between patients with an abnormal IV GTT result compared to those with a normal IV GTT result. Of the 120 patients consented, 115 completed glucose testing and 13 (11.3%) had an abnormal IV GTT. Age, race/ethnicity, parity, family history of DM, insurance status, gestational age at testing, and body mass index did not differ between those with abnormal compared to normal IV GTT results. Participants with an abnormal IV GTT result were more likely to have multifetal pregnancies (15.4% vs 0%, p=0.01). Infants delivered to patients with an abnormal IV GTT result were more likely to be LGA, have lower mean neonatal blood glucose nadirs, and require treatment with supplemental glucose (Table). Participants with an abnormal IV GTT result were more likely to have an LGA neonate and clinically significant hypoglycemia. The IV GTT is a reasonable diagnostic test for GDM-related morbidities when an oral glucose load cannot be tolerated.