Adapting fasting plasma glucose threshold for GDM diagnosis according to the population distribution - an approach to the Danish paradox

Aims: To examine third trimester fasting venous plasma glucose (FVPG) according to the distribution of a Danish population of pregnant women and identify potential local FVPG thresholds for GDM diagnosis related to risks of adverse pregnancy outcomes. Methods: In the observational Odense Child Cohort (OCC) study, 1516 women had FVPG measured at 27–28 weeks’ gestation and were considered normal by Danish criteria and remained untreated. Maternal FVPG from OCC were standardized according to the local FVPG mean and standard deviation calibrated to data from the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. Associations between maternal FVPG and clinical and anthropometric outcomes were analysed. Potential FVPG cut points were identified. Results: Unadjusted areas under the ROC curve for FVPG to discriminate for large for gestational age (LGA) and hypertensive disorders of pregnancy were 0.61 (95% CI 0.56, 0.67) and 0.57 (95% CI 0.52, 0.63), respectively. The Youden FVPG cut point for LGA was 5.5 mmol/L and 5.0 mmol/L for hypertensive disorders of pregnancy. Conclusions: This study identified a potential locally appropriate third trimester FVPG cut point between 5.5 and 5.7 mmol/L based on LGA risk in pregnancy. This cut point should be validated prospectively in other Danish cohorts.