Immanuel J, Simmons D, Desoye G, et al. - Researchers examined the predictive value of early pregnancy HbA _1c for gestational diabetes mellitus (GDM) and adverse pregnancy outcomes in obese women. Using data from the Vitamin D And Lifestyle Intervention for GDM prevention trials conducted across 9 European countries (2012–2015), they conducted post hoc analysis. Pregnant women (BMI ≥ 29 kg/m ²) were assessed for a baseline HbA _1c and oral glucose tolerance tests were performed among them at < 20 weeks, 24–28 weeks, and 35–37 weeks. Among the 869 examined women, they observed GDM prevalence of 25.9% before 20 weeks, with a further 8.6% at 24–28 weeks. Outcomes indicated limited value of early pregnancy HbA _1c for predicting either GDM or adverse outcomes in overweight/obese European women. They indicated poor sensitivity of an HbA _1c≥ 5.7% (39mmol/mol) for GDM regardless of gestation. No association of an HbA _1c ≥ 5.7% (39 mmol/mol) with greater risk of adverse outcomes was observed.