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Fasting Compared With Fed and Oral Intake Before the 1-Hour Oral Glucose Tolerance Test: A Randomized Controlled Trial. Obstetrics and gynecology Sperling, M. M., Leonard, S. A., Miller, S. E., Hurtado, J., El-Sayed, Y. Y., Herrero, T., Faig, J., Carter, S., Blumenfeld, Y. J. 2023; 141 (1): 126-133

Abstract

OBJECTIVE: To evaluate the effect of fasting compared with eating before the 1-hour oral glucose tolerance test (OGTT) on gestational diabetes mellitus (GDM) screening results.METHODS: In a single-center, prospective randomized trial, participants were randomized to: 1) fasting for 6 or more hours or 2) oral intake ("fed") within 2 hours of the 50-g, 1-hour OGTT. The 1-hour OGTT was administered after 24 weeks of gestation. A positive screen result was defined as a serum glucose level of 140 mg/dL or higher. Protocol adherence was assessed by a survey administered immediately after the OGTT. We planned to enroll 100 participants in each group to detect an absolute difference of 20 percentage points or more on the 1-hour OGTT screen-positive rate using Fisher exact test, assuming an estimated screen-positive rate of 45% in the fasting and 25% in the fed group and 10% attrition, with a two-sided alpha=0.05, power=0.8. The primary outcome was the 1-hour OGTT screen-positive rate. Secondary outcomes included mean 1-hour OGTT glucose values, GDM diagnosis, maternal and neonatal outcomes, and patient perceptions regarding the 1-hour OGTT.RESULTS: From November 2020 through April 2021, 200 participants were randomized. One hundred ninety-five completed the 1-hour OGTT (97 fasting, 98 fed). Participant surveys confirmed 97.9% (n=95) adherence to the fasting and 91.8% (n=90) adherence to the fed groups. The screen-positive rate was significantly higher in the fasting than the fed group (32.0% vs 13.3%, respectively, P=.002), as was the mean glucose value (127.7 mg/dL vs 113.3 mg/dL, P=.002). The incidence of GDM in the fasting group was 12.4% (n=12) and in the fed group was 5.1% (n=5) (P=.08). There were no significant differences in maternal or neonatal outcomes.CONCLUSION: Fasting for 6 or more hours doubled the incidence of a positive 1-hour OGTT result when compared with eating within 2 hours of the test.CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT04547023.

View details for DOI 10.1097/AOG.0000000000005013

View details for PubMedID 36701613