Red Flags
- Severe hyperglycaemia (random glucose >250 mg/dL or HbA1c >8.5%) at any antenatal visit — admit; insulin start; rule out pre-existing T1/T2DM[1]
- Diabetic ketoacidosis in pregnancy — emergency obstetric and endocrine; IV fluids, insulin, electrolytes; high fetal mortality risk[1]
- Polyhydramnios, large-for-gestational-age fetus, or maternal hypertension on GDM — escalate surveillance; consider earlier delivery and joint clinic[1]
- Postpartum persistent hyperglycaemia (fasting >100 or random >200 mg/dL) — likely undiagnosed type 2 diabetes; investigate and treat[1]
First-line treatment
Interventions
- Medical nutrition therapy[1]First-line for all GDM; carbohydrate counting and even distribution across meals and snacks; complex carbohydrates with low glycaemic index; protein and fibre to reduce postprandial peaks; total intake 1800–2400 kcal/day per BMI
- Physical activity[1]Moderate aerobic activity 30 min/day, ≥5 days/week (walking, swimming, prenatal yoga); resistance training adjunct; tailor to obstetric risk profile
- Glycaemic targets and pharmacotherapy if not met in 1–2 weeks of MNT[1]Targets: fasting <95 mg/dL, 1-h post-meal <140 mg/dL, 2-h post-meal <120 mg/dL. If fasting or post-meal exceeds target on ≥30% readings within 1 week — start pharmacotherapy
- Fetal surveillance and delivery planning[1]Growth scan + amniotic fluid index from 28 weeks every 4 weeks; CTG weekly from 36 weeks if pharmacotherapy; deliver at 39 weeks if uncomplicated GDM, 38 weeks if poor control or macrosomia
- Postpartum management[1]Stop GDM-specific therapy at delivery; encourage breastfeeding (reduces future T2DM risk); 75 g OGTT at 6–12 weeks; annual diabetes screening; preconception counselling for next pregnancy
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Insulin (basal ± rapid)[1] | Insulin therapy | Start NPH 0.1 U/kg/day at night ± rapid analogue 0.05 U/kg per meal; titrate by SMBG. Total dose typically increases 50% by third trimester | Not applicable — pregnancy use only | First-line pharmacotherapy in GDM; aspart, lispro, glargine, detemir all safe in pregnancy; teach self-administration and hypoglycaemia recognition |
| Metformin[1] | Biguanide | 500 mg PO BD, titrate to 1000 mg BD as tolerated | Not applicable — pregnancy use only | Acceptable alternative or adjunct to insulin (FOGSI 2023, NICE NG3); long-term safety good but crosses placenta — counsel on uncertainties; ~30–50% require insulin addition |
| Glyburide (alternative — not preferred)[1] | Sulfonylurea | 2.5–5 mg PO BD; max 20 mg/day | — | Less preferred than insulin or metformin due to neonatal hypoglycaemia and macrosomia signal; reserve for cases where insulin and metformin both unsuitable |
Insulin (basal ± rapid)[1]
Insulin therapy
- Adult
- Start NPH 0.1 U/kg/day at night ± rapid analogue 0.05 U/kg per meal; titrate by SMBG. Total dose typically increases 50% by third trimester
- Paediatric
- Not applicable — pregnancy use only
First-line pharmacotherapy in GDM; aspart, lispro, glargine, detemir all safe in pregnancy; teach self-administration and hypoglycaemia recognition
Metformin[1]
Biguanide
- Adult
- 500 mg PO BD, titrate to 1000 mg BD as tolerated
- Paediatric
- Not applicable — pregnancy use only
Acceptable alternative or adjunct to insulin (FOGSI 2023, NICE NG3); long-term safety good but crosses placenta — counsel on uncertainties; ~30–50% require insulin addition
Glyburide (alternative — not preferred)[1]
Sulfonylurea
- Adult
- 2.5–5 mg PO BD; max 20 mg/day
- Paediatric
- —
Less preferred than insulin or metformin due to neonatal hypoglycaemia and macrosomia signal; reserve for cases where insulin and metformin both unsuitable
Safety-net
- Test blood sugar as instructed and bring the log to every appointment — adjustments depend on the actual numbers[1]
- Sick-day rules — keep eating and drinking small amounts; check sugar more often; if vomiting, ketones present, or sugars erratic — call for review[1]
- After delivery, do not skip the 6-week glucose test — this is when undiagnosed type 2 diabetes is caught early[1]
Referral criteria
- All women with GDMJoint obstetric and diabetes/endocrine clinic[1]
- Severe hyperglycaemia (HbA1c >8.5% or DKA)Endocrine same-day; consider admission[1]
- Macrosomia, polyhydramnios, or fetal compromise on surveillanceMaternal-fetal medicine and obstetrics[1]
- Persistent postpartum hyperglycaemia or HbA1c ≥6.5% at 6–12 weeksDiabetes clinic[1]
Clinical summary
Screening, glycaemic targets, lifestyle and pharmacological therapy for hyperglycaemia first detected in pregnancy and postpartum follow-up.