A 28-year-old primigravida from Delhi presents at 24 weeks of gestation for routine antenatal care. She is asymptomatic with a BMI of 26 kg/m². Fasting blood glucose is 95 mg/dL and 2-hour post-75 g oral glucose tolerance test (OGTT) value is 168 mg/dL. Her HbA1c is 5.8%. She has no personal history of diabetes but her mother was diagnosed with type 2 diabetes at age 45. What is the most appropriate next step in management?

Explanation

## Diagnosis and Management of Gestational Diabetes ### Diagnostic Criteria (IADPSG/WHO 2013) **Key Point:** A single abnormal value on 75 g OGTT at 24–28 weeks is diagnostic of gestational diabetes mellitus (GDM). The diagnostic thresholds are: - Fasting: ≥92 mg/dL - 1-hour: ≥180 mg/dL - 2-hour: ≥153 mg/dL In this case, the 2-hour value of 168 mg/dL exceeds 153 mg/dL, meeting diagnostic criteria for GDM. ### Management Algorithm ```mermaid flowchart TD A[OGTT at 24-28 weeks]:::outcome --> B{Any value abnormal?}:::decision B -->|No| C[Repeat at 32 weeks if risk factors]:::action B -->|Yes| D[Diagnose GDM]:::outcome D --> E[Medical Nutrition Therapy]:::action E --> F[Home glucose monitoring]:::action F --> G{Target achieved?}:::decision G -->|Yes| H[Continue MNT + monitoring]:::action G -->|No| I[Add insulin/oral agent]:::action ``` ### First-Line Management **High-Yield:** Medical Nutrition Therapy (MNT) is the first-line intervention for all newly diagnosed GDM cases: - Individualized diet by dietitian (carbohydrate counting, glycemic index awareness) - Target: 40–45% carbohydrates, 20–25% protein, 30–35% fat - Regular physical activity (150 min/week if no contraindications) - Home capillary glucose monitoring (fasting, 2 hours post-meals) - Target glucose levels: fasting <95 mg/dL, 2-hour postprandial <120 mg/dL **Clinical Pearl:** Approximately 80–85% of GDM cases are managed successfully with MNT alone; pharmacotherapy is added only if targets are not met after 2 weeks of strict dietary adherence. ### Why Immediate Insulin Is Premature Insulin is indicated only if: - MNT fails to achieve target glucose levels after 10–14 days, OR - Fasting glucose >110 mg/dL at diagnosis, OR - Severe hyperglycemia (random >200 mg/dL) with symptoms This patient has a single abnormal 2-hour value; insulin is not first-line. ### Monitoring and Follow-up - Repeat fasting glucose weekly or biweekly - Ultrasound for fetal growth at 28 and 34 weeks - Non-stress test if insulin-requiring or poor glycemic control - Delivery planning at 39 weeks (or earlier if complications) [cite:ACOG Practice Bulletin 190, IADPSG 2013]