INTRODUCTION: ACOG recommends early screening for glucose intolerance in obese women, who are at increased risk of insulin resistance. We aimed to assess the risk of developing GDM based on the value of a normal early 50g oral glucose challenge test (GCT). METHODS: Retrospective cohort of non-anomalous singleton pregnancies with maternal BMI ≥40 at one institution, 2013–2017. Pregnancies with multiple gestation, late entry to care, type 1 or 2 diabetes, and missing diabetes-screening information are excluded. Primary outcome was development of GDM. Secondary outcomes include fetal growth restriction, fetal macrosomia, gestational age at delivery, large for gestational age, delivery BMI, total pregnancy weight gain, labor induction, shoulder dystocia, and cesarean delivery. Bivariate statistics compare demographics, pregnancy complications and delivery characteristics of women with early GCT >100 and women who with early GCT 101–134. Regression models used to estimate odds of primary outcome. RESULTS: Of 169 women, 66 (39%) had an early GCT <100, and 103 (61%) had an early GCT of 101–134. Women with low normal eGCT were more likely to use recreational drugs (P=.03). Other baseline demographics did not differ. The rate of GDM was low in this population (5.3%), with no difference in the rate of GDM between women with a low normal eGCT and high normal eGCT (P=.9). The median neonatal birthweight was higher in the normal GCT group as compared to the low GCT (P=.03). CONCLUSION: Among women with class 3 obesity, the specific value of an early normal GCT was not predictive of developing GDM by the third trimester.