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Intermediate-acting Insulin Pregnancy: Preferred basal insulin in pregnancy (NICE NG3) — most data available; monitor closely as requirements change.

Insulin NPH (Isophane)

Brand names: Humulin I, Insulatard

Adult dose

Dose: Type 1 DM (basal component of basal-bolus): 0.2–0.4 units/kg OD or BD; Type 2 DM: 10 units OD at bedtime, titrated to fasting glucose
Route: Subcutaneous injection
Frequency: Once or twice daily (typically at bedtime or BD)
Max: Individualised — no absolute maximum
MHRA safety requirement: prescribe by brand name (Humulin I or Insulatard). Cloudy suspension — must be gently rolled/inverted 10 times before injection to resuspend. Onset 1–2h, peak 4–12h, duration 12–24h. NICE NG3 recommends NPH as first-line basal insulin in pregnancy.

Paediatric dose

Dose: 0.2 units/kg
Route: Subcutaneous injection
Frequency: Once or twice daily
Max: Individualised per glycaemic target
BNFc: No lower age limit — used from infancy under specialist supervision. Seek paediatric endocrinology guidance.

Dose adjustments

Renal

Insulin requirements may decrease in renal impairment — monitor closely.

Hepatic

Impaired hepatic gluconeogenesis increases hypoglycaemia risk — monitor glucose carefully.

Paediatric weight-based calculator

BNFc: No lower age limit — used from infancy under specialist supervision. Seek paediatric endocrinology guidance.

Clinical pearls

  • NPH has more variable absorption and higher nocturnal hypoglycaemia risk than long-acting analogues (glargine, detemir, degludec) — NICE NG17 prefers analogues for Type 1 DM
  • Preferred in pregnancy (NICE NG3) — most safety data
  • Antidote for hypoglycaemia: oral glucose if conscious; IM glucagon 1mg or IV dextrose 10% 150mL if unconscious
  • Cloudy insulin — if clear after mixing attempt, do not use (may indicate denaturation)

Contraindications

  • Hypoglycaemia
  • Hypersensitivity to isophane insulin

Side effects

  • Hypoglycaemia (particularly nocturnal)
  • Injection site lipohypertrophy
  • Oedema
  • Weight gain

Interactions

  • Beta-blockers — mask hypoglycaemia
  • Corticosteroids, thiazides — antagonise glucose-lowering effect
  • Alcohol — potentiates hypoglycaemia

Monitoring

  • Fasting glucose (4–7 mmol/L target)
  • Nocturnal glucose (hypoglycaemia detection)
  • HbA1c 3 monthly
  • Injection site assessment

Reference: BNFc; BNF 90; NICE NG3 (Diabetes in Pregnancy); NICE NG17 (Type 1 DM); MHRA Insulin Safety Alert. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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