A 28-year-old primigravida at 24 weeks of gestation presents for routine antenatal care. She is asymptomatic with no significant past medical history. Her BMI is 26 kg/m². You perform a 75 g oral glucose tolerance test (OGTT) as per screening protocol. The results are: fasting 95 mg/dL, 1-hour 185 mg/dL, 2-hour 155 mg/dL. What is the most appropriate next step in management?