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Long-Acting Insulin Analogue (Basal) Pregnancy: Compatible — insulin is mainstay of glycaemic management in pregnancy; switch from oral agents

Insulin Glargine

Brand names: Lantus, Toujeo (U300), Abasaglar (biosimilar)

Adult dose

Dose: Type 1: 0.2–0.4 units/kg OD (adjust to fasting glucose target 4–7 mmol/L). Type 2 starting: 10 units OD, titrate by 2 units every 3 days.
Route: Subcutaneous injection
Frequency: Once daily (same time each day — usually bedtime or morning)
Max: No fixed maximum — titrate to blood glucose
Lantus (U100) and Toujeo (U300) are NOT interchangeable unit-for-unit — different concentrations. Abasaglar is biosimilar to Lantus. Do NOT mix with other insulins.

Paediatric dose

Dose: 0.2 units/kg
Route: Subcutaneous
Frequency: Once daily
Max: Adjusted to blood glucose — no fixed maximum
Concentration: 100 units/mL (U100) or 300 units/mL (U300) units/ml
Licensed for children ≥2 years (Lantus/Abasaglar). Toujeo not licensed in children <18. Start lower, titrate to target.

Dose adjustments

Renal

Dose reduction may be needed — renal failure reduces insulin clearance and hypoglycaemia risk increases

Hepatic

Dose reduction may be needed in hepatic failure (reduced gluconeogenesis increases hypoglycaemia risk)

Paediatric weight-based calculator

Licensed for children ≥2 years (Lantus/Abasaglar). Toujeo not licensed in children <18. Start lower, titrate to target.

Clinical pearls

  • Consistent injection time essential — glargine has no pronounced peak but reproducible action over 24h
  • Lipohypertrophy: rotate injection sites systematically; check for lumps at each visit
  • Toujeo (U300): smaller injection volume, slightly flatter profile — may cause less nocturnal hypoglycaemia
  • If transitioning from NPH to glargine: unit-for-unit initially; may need dose reduction

Contraindications

  • Hypoglycaemia (acute)

Side effects

  • Hypoglycaemia
  • Injection site reactions (lipohypertrophy with poor rotation)
  • Weight gain
  • Oedema
  • Lipodystrophy

Interactions

  • Alcohol — potentiates hypoglycaemia
  • Beta-blockers — mask tachycardia of hypoglycaemia (sweating preserved)
  • Corticosteroids — raise blood glucose (higher insulin requirements)
  • ACEi — may enhance hypoglycaemic effect
  • Octreotide — variable effects on insulin requirements

Monitoring

  • Fasting blood glucose (daily)
  • HbA1c (every 3 months)
  • Injection sites (rotation compliance)
  • Hypoglycaemia frequency and severity
  • Weight

Reference: BNFc; BNF; NICE NG17 (T1DM); NICE NG28 (T2DM); BNF for Children. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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