Fasting Versus Fed: Effect of Oral Intake Prior to the Glucose Tolerance Test in Pregnancy

Gestational diabetes (GDM) complicates approximately 400,000 pregnancies in the United States annually and is associated with significant adverse pregnancy outcomes, including increasing the lifetime risk of type 2 diabetes. The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women undergo GDM screening between 24-28 weeks gestation utilizing a 1-hour oral glucose tolerance test that was designed to be administered without regard to the last meal or time of day. However, studies suggest that the timing of one's last meal prior to the 1-hour GDM screen may have a significant impact on GDM screening glucose levels. In addition, providers routinely alter the timing of the 1-hour GDM screen based on patients' self reported oral intake prior to the exam. The investigators plan to conduct a prospective randomized trial comparing a 6-hour fast versus liberal oral intake within 2 hours prior to the glucose tolerance test in pregnancy in order to evaluate the effect of the fasting versus the fed state on routine GDM screening results.

Inclusion criteria

• Pregnant patients 18 years and older
• Singleton gestation
• Pregnancy managed at Lucile Packard Children's Hospital (LPCH) Stanford outpatient obstetrics clinic
• Planned delivery at Lucile Packard Children's Hospital (LPCH) Stanford Labor and Delivery unit

Exclusion criteria

• Pregestational diabetes
• Gestational diabetes diagnosed in the 1st trimester
• Less than 18 years of age
• Planned delivery outside LPCH
• Diabetes medication use prior to pregnancy
• Inability to give informed consent
• Chronic steroid use in pregnancy
• Less than 24 weeks of gestation at the time of the 1 hour oral glucose tolerance test
• Prior history of bariatric surgery
• Multifetal gestation