Metformin

Metformin is commonly prescribed for type 2 diabetes, often as a first-line medicine alongside diet and physical activity. It may also be used in some other situations as directed by a specialist.

Your GP or diabetes team will agree targets and follow-up with you.

Metformin mainly reduces glucose production by the liver and improves the body’s response to insulin. It does not usually cause low blood sugar when used alone.

It is one part of a broader plan that may include other medicines or insulin if needed.

Metformin is often started at a low dose with meals to limit stomach upset, then increased gradually. Modified-release tablets may be prescribed if standard tablets are poorly tolerated.

Swallow tablets whole unless your prescriber advises otherwise. Follow the schedule you have been given.

Common effects can include nausea, diarrhoea, stomach cramps, or metallic taste, especially at the start. These often improve over time.

Taking metformin with food, as advised, can help. Persistent symptoms should be discussed with your GP or pharmacist.

A rare but serious condition called lactic acidosis can occur; risk is higher with severe kidney problems, dehydration, or certain other illnesses. Seek urgent care if you become very unwell with deep breathing, severe fatigue, or abdominal pain.

If you are due to have a scan with contrast dye, tell the team you take metformin — they may advise pausing it temporarily.

If you miss a dose, take it with food when you remember unless it is close to the next dose. Do not double the dose.

If you are unsure, your pharmacist can confirm what to do for your tablet type and schedule.

Metformin may not be suitable with severe kidney impairment, acute conditions that affect kidneys or hydration, or certain other situations your prescriber will assess.

Always mention liver disease, heart failure, and alcohol use, as these can influence suitability and monitoring.

Some medicines can affect metformin or kidney function; examples include certain contrast agents and some drugs cleared by the kidneys.

Your prescriber or pharmacist checks combinations; report new prescriptions or over-the-counter purchases.

Diabetes in pregnancy is usually managed with specialist input; metformin may or may not be used depending on individual circumstances.

If you are pregnant, planning pregnancy, or breastfeeding, your GP or specialist will advise on the safest approach.

Kidney function (eGFR) is typically checked before and during metformin therapy. Vitamin B12 levels may be monitored long term in some people.

HbA1c and other diabetes checks will be arranged as part of routine diabetes care.

Other classes of diabetes medicines (for example, SGLT2 inhibitors, DPP-4 inhibitors, GLP-1 receptor agonists, or insulin) may be added or used instead depending on your needs and heart or kidney health.

Your diabetes team will discuss options in line with NICE pathways where applicable.