EBM Focus: Two Steps to the “Best” Screening Test for Gestational Diabetes In this EBM Focus article, DynaMed® editors discuss a new trial attempting to determine which screening strategy is best for gestational diabetes. April 8, 2021 The impact of gestational diabetes mellitus on perinatal outcomes is well-established, and higher maternal hyperglycemia seems to correspond to worse clinical outcomes. Universal screening for gestational diabetes at 24-28 weeks gestation (or earlier if there are additional risk factors) is recommended using one of two clinically accepted methods: a one-step approach that involves a fasting blood glucose and then blood glucose checks at one and two hours after a 75 g glucose challenge, or the two-step method which involves a blood glucose check one hour after a 50 g challenge and a reflex three-hour glucose tolerance test for those who screen positive. Choice of screening method and diagnostic cutoffs are often institution-specific, without strong evidence at this point for a “best test.”