Metformin

Metformin is the most widely prescribed medication for type 2 diabetes and is recommended as the first-line drug treatment by all major diabetes guidelines worldwide, including those adopted in Nigeria. It works primarily by reducing the amount of glucose produced by the liver and improving the body's sensitivity to insulin. Unlike some other diabetes drugs, metformin does not cause weight gain and rarely causes hypoglycaemia (dangerously low blood sugar) when used alone. It has an excellent long-term safety record, is inexpensive, and is available at most Nigerian health facilities.

• First-line treatment of type 2 diabetes mellitus: in combination with lifestyle changes (healthy diet and regular exercise) • Pre-diabetes: to delay or prevent progression to type 2 diabetes in high-risk individuals • Polycystic ovary syndrome (PCOS): helps restore menstrual regularity and reduce insulin resistance • Gestational diabetes: used in some cases when insulin is not available or appropriate • Prevention of weight gain in people taking antipsychotic medications • Some evidence for reduction of cardiovascular events in people with type 2 diabetes

Starting dose: • Begin low and increase gradually to reduce gastrointestinal side effects • Typical starting dose: 500 mg once or twice daily with meals • Increase gradually every 1–2 weeks as tolerated • Standard maintenance dose: 1,000–2,000 mg per day in 2–3 divided doses • Maximum dose: 3,000 mg per day (rarely needed) Important instructions: • Always take with food or immediately after meals: this significantly reduces nausea and stomach upset • Swallow tablets whole with a glass of water • Extended-release (XR/ER) tablets should not be crushed or chewed • Take metformin at the same time(s) each day to maintain steady blood levels • Metformin must be used alongside a healthy diet and regular physical activity: it is not a replacement for lifestyle change • Do not stop taking metformin without consulting your doctor, even if blood sugar appears normal

Very common (especially when starting or increasing dose): • Nausea, vomiting • Diarrhoea • Stomach cramps and discomfort • Loss of appetite • Metallic taste in the mouth These effects are usually temporary and improve after 2–4 weeks. Starting at a low dose and taking with food minimises them. Rare but serious: • Vitamin B12 deficiency: long-term metformin use can reduce B12 absorption; check levels annually after several years of use • Lactic acidosis: a very rare but potentially fatal build-up of lactic acid in the blood, usually in people with severely impaired kidney function; symptoms include muscle pain, weakness, difficulty breathing, abdominal pain, and dizziness — seek emergency care Metformin alone does NOT cause hypoglycaemia (low blood sugar). Hypoglycaemia only occurs if combined with other diabetes medications or insulin.

• Alcohol: increases risk of lactic acidosis; avoid excessive alcohol intake • Contrast dye (iodinated): stop metformin 48 hours before procedures using contrast media • ACE inhibitors, diuretics, and NSAIDs: can impair kidney function and increase lactic acidosis risk • Cimetidine: increases metformin blood levels • Topiramate and other carbonic anhydrase inhibitors: may increase lactic acidosis risk • Insulin and other diabetes medications: risk of hypoglycaemia when combined: doses may need adjustment

• Store at room temperature (below 30°C) away from heat, moisture, and direct sunlight • Keep in original packaging • Keep out of reach of children