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

Explanation

## Diagnostic Criteria for Gestational Diabetes **Key Point:** The diagnosis of gestational diabetes mellitus (GDM) using the 75-g OGTT is established when ANY ONE of the following thresholds is exceeded: - Fasting glucose ≥92 mg/dL - 1-hour glucose ≥180 mg/dL - 2-hour glucose ≥153 mg/dL ## Analysis of This Case This patient meets diagnostic criteria on TWO counts: 1. 1-hour glucose of 185 mg/dL (exceeds 180 mg/dL threshold) 2. 2-hour glucose of 155 mg/dL (exceeds 153 mg/dL threshold) **High-Yield:** The IADPSG (International Association of Diabetes and Pregnancy Study Groups) criteria, adopted globally including India, require only ONE abnormal value to diagnose GDM. This single-step approach has replaced the older two-step method in most high-income and middle-income settings. ## Management of Confirmed GDM Once diagnosed, the standard approach includes: 1. **Dietary counseling** — carbohydrate counting, portion control, balanced macronutrients 2. **Self-monitoring of blood glucose** — fasting and postprandial targets (fasting <95 mg/dL, 2-hour postprandial <120 mg/dL) 3. **Pharmacotherapy** — insulin or metformin if glycemic targets not achieved within 2 weeks of lifestyle modification **Clinical Pearl:** Insulin is the first-line agent in pregnancy because it does not cross the placenta and has the longest safety record. Metformin is increasingly used as an alternative, particularly in resource-limited settings. ## Why Other Options Are Incorrect - **Repeat OGTT in 4 weeks:** Unnecessary delay; diagnosis is already confirmed. - **Insulin immediately without trial of diet:** Premature; lifestyle modification should be attempted first for 2 weeks. - **Dietary modification alone without pharmacotherapy plan:** Incomplete; the stem indicates confirmed GDM requiring structured management with a clear escalation pathway. [cite:IADPSG Consensus Report 2010; Harrison 21e Ch 379]