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Alpha-glucosidase Inhibitor Pregnancy: Contraindicated — insufficient data. Use insulin in pregnancy.

Acarbose

Brand names: Glucobay

Adult dose

Dose: Starting: 50mg OD with first bite of meal for 4 weeks; increase to 50mg TDS for 4 weeks; maximum 100mg TDS
Route: Oral (chewed with first bite of meal or swallowed whole with water before meal)
Frequency: Three times daily with meals
Max: 100mg TDS (300mg daily)
Reduces postprandial glucose by delaying carbohydrate absorption. GI side effects are dose-limiting and common. Less effective than other agents — mainly used as add-on when other agents not tolerated. Titrate slowly to reduce GI effects.

Paediatric dose

Route: Oral
Frequency: Three times daily
Max: Not applicable
Not licensed under 18 years. Seek specialist opinion.

Dose adjustments

Renal

eGFR <30: avoid. Serum levels increase significantly in severe renal impairment.

Hepatic

Avoid in hepatic impairment — hepatotoxicity reported at high doses.

Clinical pearls

  • CRITICAL: hypoglycaemia in patients on acarbose must be treated with GLUCOSE (not Lucozade/sucrose) — acarbose inhibits intestinal sucrase and disaccharide digestion, so sucrose will not be absorbed rapidly enough
  • GI side effects are very common and lead to high discontinuation rates — counsel patients at initiation that flatulence improves over weeks
  • Modest HbA1c reduction (~0.5%) — used mainly in patients intolerant to other agents
  • STOP-NIDDM trial: acarbose reduced progression from IGT to T2DM by 36% and reduced CV events

Contraindications

  • Inflammatory bowel disease
  • Colonic ulceration
  • Intestinal obstruction/partial obstruction
  • Chronic intestinal disease with malabsorption
  • Hernia (risk of distension)
  • eGFR <30
  • Cirrhosis

Side effects

  • Flatulence (very common, dose-limiting)
  • Diarrhoea
  • Abdominal pain and bloating
  • Elevated liver enzymes (rare, dose-dependent)
  • Skin reactions (rare)

Interactions

  • Digestive enzyme preparations — antagonise acarbose (avoid combination)
  • Cholestyramine — additive glucose-lowering (take separately)
  • Insulin/sulphonylureas — hypoglycaemia may occur; antidote must be glucose (NOT sucrose — acarbose blocks sucrase)

Monitoring

  • Blood glucose (postprandial)
  • HbA1c
  • Liver enzymes (at 6–12 months when using high doses)
  • GI symptoms

Reference: BNFc; BNF 90; NICE NG28 (Type 2 DM); STOP-NIDDM Trial. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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