Performance of early pregnancy HbA1c for predicting gestational diabetes mellitus and adverse pregnancy outcomes in obese European women

Abstract

AimsTo investigate the performance of early pregnancy HbA1c for predicting gestational diabetes mellitus (GDM) and adverse pregnancy outcomes in obese women. MethodsPost hoc analysis using data from the Vitamin D And Lifestyle Intervention for GDM prevention trials conducted across 9 European countries (2012–2014). Pregnant women (BMI ≥ 29 kg/m2) underwent a baseline HbA1c and oral glucose tolerance tests at < 20 weeks, 24–28 weeks, and 35–37 weeks. Women with GDM were referred for treatment. ResultsAmong the 869 women tested, the prevalence of GDM was 25.9% before 20 weeks, with a further 8.6% at 24–28 weeks. The areas under the curves for HbA1c at the two time points were 0.55 (0.50–0.59) and 0.54 (0.47–0.61), respectively. An early HbA1c ≥ 5.7% (39 mmol/mol) (N = 111) showed low sensitivity (18.2%) with 89.1% specificity for GDM before 20 weeks, at 24–28 weeks (sensitivity of 8.0% and specificity of 88.6% after excluding early GDM), and throughout gestation (sensitivity of 15.9% and specificity of 89.4%). The ≥ 5.7% (39 mmol/mol) threshold was significantly associated with concurrent GDM before 20 weeks (adjusted OR (aOR) 2.77(1.39–5.51)) and throughout gestation (aOR 1.72 (1.02–2.89)), but not adverse pregnancy outcomes. ConclusionsEarly pregnancy HbA1c is of limited use for predicting either GDM or adverse outcomes in overweight/obese European women.