Fasting Compared With Fed and Oral Intake Before the 1-Hour Oral Glucose Tolerance Test: A Randomized Controlled Trial.

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 α=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.

Early Screening and Treatment of Women with Prediabetes: A Randomized Controlled Trial.

OBJECTIVE: To examine whether women with prediabetes benefit from early treatment for gestational diabetes mellitus (GDM). STUDY DESIGN: Women with a glycosylated hemoglobin A1C (A1C) of 5.7 to 6.4% at <14 weeks were recruited. Participants were randomized to usual care or treatment for GDM with diet, blood glucose monitoring, and insulin as needed. The primary outcome was a 75-g oral glucose tolerance test at 26 to 28 weeks. Secondary outcomes included cesarean delivery, birthweight, weight gain, and A1C change. RESULTS: Between May 2012 and June 2014, 95 women were enrolled and 83 had data for analysis; 42 were randomized to treatment and 41 to usual care. The groups were similar in baseline characteristics with 40% obese. There was no difference in the primary outcome (treatment 45.2% vs. control 56.1%; relative risk [RR] 0.80; 95% confidence interval [CI] 0.53-1.24) except that women in the treatment group had a significantly lower A1C over time than women in the control group (p = 0.04). Nonobese women (n = 50) treated for GDM experienced a 50% reduction in GDM compared with controls (29.6 vs. 60.9%; RR 0.49; 95% CI 0.25-0.95). CONCLUSION: Early treatment for women with a first-trimester A1C of 5.7 to 6.4% did not significantly reduce the risk of GDM except in nonobese women.

Continuous glucose monitoring in pregnancy: new frontiers in clinical applications and research.

Current treatment of diabetes in pregnancy relies on intermittent self-monitoring of blood glucoses using finger sticks to monitor capillary blood glucoses. Continuous glucose monitoring (CGM) systems are an emerging technology that allow frequent glucose measurements (every 5 min) and the ability to monitor glucose trends in real time. Although these devices are currently expensive and mildly invasive to use, there is huge potential for their use in both the research and clinical realms. From a research perspective, there is the potential to better understand glucose metabolism in pregnancy, both in patients with and without diabetes. For the treating clinician, CGM has the potential to improve detection of hyperglycemic excursions as well as asymptomatic hypoglycemia and the data to improve management of glucose levels in diabetes patients. In this article, we review current literature examining use of CGM in both research and clinical applications.