Correlation between fasting glucose in the first trimester and glucose challenge test in the second

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Maternal-Fetal Medicine

Background:

• Gestational diabetes mellitus (GDM) screening typically occurs in the second trimester.
• Early pregnancy glucose levels may offer predictive value for GDM.
• Assessing the correlation between first-trimester fasting glucose and second-trimester glucose challenge test (GCT) is crucial for optimizing screening protocols.

Purpose of the Study:

• To investigate the statistical correlation between first-trimester fasting plasma glucose (FPG) and second-trimester 50-g glucose challenge test (GCT) levels.
• To determine the clinical utility of early pregnancy FPG measurements in predicting GCT outcomes.

Main Methods:

• A cohort of 612 healthy pregnant women with singleton pregnancies were analyzed.
• Fasting plasma glucose was measured during the first trimester.
• A 50-g glucose challenge test was administered at 24-28 weeks' gestation in 425 women.

Main Results:

• The mean first-trimester FPG was 77.8 ± 9.7 mg/dL, and the mean 1-hour post-GCT level was 109.1 ± 29.8 mg/dL.
• A statistically significant but weak positive correlation (r=.26, P < .001) was observed between first-trimester FPG and second-trimester GCT levels.
• Linear regression analysis indicated a low explanatory power (r²=.10) for first-trimester FPG and maternal weight in predicting second-trimester GCT results.

Conclusions:

• The correlation between early pregnancy fasting glucose and the second-trimester glucose challenge test is low.
• Routine fasting glucose measurement in the first trimester does not provide significant clinical benefit for predicting gestational diabetes.
• Current GDM screening guidelines focusing on the second trimester remain appropriate.