Gestational Diabetes — Managing GDM Through Pregnancy

Gestational diabetes mellitus (GDM) is glucose intolerance first recognised in pregnancy. It affects 10–20% of Indian pregnancies. This page covers diagnosis, management, fetal monitoring and long-term implications for mother and child.

1. Why GDM matters

Untreated GDM causes excessive fetal growth (macrosomia), birth complications, polyhydramnios, preterm birth, and increased caesarean rates. For the baby: shoulder dystocia risk, neonatal hypoglycaemia, jaundice, and lifelong elevated diabetes risk. For the mother: long-term type 2 diabetes risk approaches 50% within 10 years.

2. Screening, when and how

Universal screening between 24–28 weeks via 75 g oral glucose tolerance test (OGTT). Earlier screening at booking visit (8–10 weeks) for high-risk women, prior GDM, BMI over 25, family history, prior macrosomic baby, PCOS, age over 25 in Indian populations. WHO/IADPSG criteria are standard.

3. Diagnostic thresholds

Fasting glucose: 92 mg/dL or higher. 1-hour post 75g glucose: 180 mg/dL or higher. 2-hour post 75g glucose: 153 mg/dL or higher. Any one value at or above threshold confirms GDM.

4. Diet, the cornerstone

Carbohydrate distribution across 3 meals plus 2–3 snacks; lower glycaemic-load choices; adequate protein at each meal; reduced refined carbohydrates and sugary drinks. Most women achieve glycaemic control with diet and exercise alone. Specific Indian-diet adaptations (replacing some white rice with millets, adding more dal/legume protein, including non-starchy vegetables) typically work well.

5. Exercise

30 minutes of moderate activity most days (walking, prenatal yoga, swimming). Post-meal walking particularly effective for lowering post-prandial glucose. Avoid contact sports, very high-intensity activity, and exercise associated with falls risk.

6. Glucose monitoring

Self-monitoring of blood glucose (SMBG) — fasting plus 1- or 2-hour post-meal values. Targets: fasting under 95 mg/dL; 1-hour post-meal under 140 mg/dL; 2-hour post-meal under 120 mg/dL. Records reviewed at each antenatal visit. Continuous glucose monitoring increasingly used in selected cases.

7. When medication is needed

If diet and exercise do not achieve glycaemic targets within 1–2 weeks. Insulin remains the gold standard, short-acting before meals, basal for fasting glucose if needed. Metformin is acceptable alternative for some women but crosses placenta. Lifestyle continues alongside medication.

8. Postpartum care

Glucose normalises after delivery in most women. Repeat 75g OGTT at 6 weeks postpartum to confirm. Lifetime risk of type 2 diabetes is high (about 50% within 10 years). Annual glucose check, weight management, exercise, breastfeeding (protective), and metformin in selected cases reduce future risk substantially.