Pregnant Women Become Sweeter: A Population-Based Study of Trends in Glucose Challenge Test Results over a Decade

Background: Glucose challenge tests (GCTs) are widely used to screen for gestational diabetes mellitus. Women with high normal GCT results may be at increased risk for immediate obstetric complications and future diabetes. We analyzed the ∼10-year trend in mean GCT results and incidence of high normal (125-140 mg/dL) and abnormal GCT results (>140 mg/dL) in a large cohort of women in Israel. Materials and Methods: Data on all GCTs performed between 2005 and 2016 were gathered from the computerized database of the Central District of Clalit Health Services, the largest Health Maintenance Organization in Israel. Trends over time were studied by time series analysis, and a multivariable logistic model was constructed to study the risk for abnormal results, while adjusting for maternal age and body mass index (BMI). Results: Altogether 101,359 GCTs were analyzed. Over the study period, mean maternal age increased from 28.7 ± 5.1 to 30.1 ± 5.1 years and mean GCT results from 101.7 to 114.6 mg/dL (p < 0.001, for both), whereas the incidence of women with abnormal GCT (>140 mg/dL) increased from 10.6% to 18.1% (p < 0.001) and of those with high normal GCT (>125 mg/dL) from 20.2% to 31.3% (p < 0.001). A multivariable logistic model revealed that later years were associated with an increased risk for abnormal GCT result, while adjusting for maternal age and BMI (adjusted odds ratio = 1.07; 95% confidence interval 1.07-1.08). Conclusions: Over ∼10 years, mean GCT results and high GCT incidence have significantly increased. These findings are in line with the worldwide diabetes epidemic and demonstrate the worsening in glucose metabolism also in relatively young women.