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

To determine if there is a statistically significant correlation between the plasma glucose level obtained following a glucose challenge test at 24-28 weeks' gestation and the fasting plasma glucose level in the first trimester.

The study population included 621 healthy women with singleton pregnancies followed in the antenatal clinic of the Hadassah Medical Center, with a fasting plasma glucose level performed during the first trimester. Nine women had fasting blood glucose levels above 105 mg/dL and were excluded from the study. Of the remaining 612 women, 425 (69%) had 50-g glucose challenge tests at 24-28 weeks' gestation.

The mean (+/-standard deviation [SD]) first-trimester fasting glucose level was 77.8+/-9.7 mg/dL and the mean (+/-SD) glucose level 1 hour after the second-trimester glucose challenge test was 109.1+/-29.8 mg/dL. The fasting plasma glucose level and the glucose level following the glucose challenge correlated significantly but not strongly (=.26, P < .001). However, using a linear regression model in which fasting plasma glucose level and maternal weight were explanatory variables and glucose level following the glucose challenge test was the dependent variable resulted in a very low r2 (.10).

The correlation between the plasma glucose level obtained following a glucose challenge test and the fasting plasma glucose level in the first trimester is low, indicating that fasting glucose measurement early in pregnancy has no clinical benefits.