Endocrinology · Biguanide
Metformin
Dose
500 mg OD with food → titrate to 1 g BD–TDS (max 2 g/d)
Mechanism
↓ Hepatic gluconeogenesis, ↑ peripheral insulin sensitivity
Indications
- • T2DM first-line
- • PCOS (off-label)
Contraindications
- • eGFR <30
- • Acute illness with hypoperfusion (lactic acidosis risk)
Dose adjustment
eGFR 30–45: max 1 g/d; hold during iodinated contrast if eGFR <30
Use
Weight-neutral, no hypoglycaemia monotherapy.
Monitoring
eGFR annually (6-monthly if impaired), B12.
Side effects
- • GI upset
- • B12 deficiency
- • Lactic acidosis (rare)
Related in WardRound
Always confirm dose against your local formulary / BNF before prescribing.
