A 32-year-old multigravida (G3P2L2) from Delhi attends her second antenatal visit at 16 weeks of gestation. Her first pregnancy was uncomplicated, but her second pregnancy was complicated by gestational diabetes mellitus (GDM) diagnosed at 24 weeks, managed with diet and insulin, with delivery of a 3.8 kg baby. Current booking investigations show fasting blood glucose 95 mg/dL and random blood glucose 118 mg/dL. She has a BMI of 28 kg/m² and no family history of diabetes. What is the most appropriate screening strategy for GDM in this patient?