About metformin (2024)

Metformin is a medicine used to treat type 2 diabetes and gestational diabetes. It's also used to help prevent type 2 diabetes if you're at high risk of developing it.

Type 2 diabetes is a condition where the body does not make enough insulin, or the insulin that it makes does not work properly. This can cause high blood sugar levels (hyperglycaemia).

Metformin lowers your blood sugar levels by improving the way your body handles insulin.

It's usually prescribed for diabetes when diet and exercise alone have not been enough to control your blood sugar levels.

Metformin is also sometimes used to manage symptoms of polycystic ovary syndrome (PCOS), a condition that affects how the ovaries work. It is not officially approved for PCOS.

Metformin treats PCOS by lowering insulin and blood sugar levels. This can also improve ovulation and encourage regular periods, even if you do not have diabetes.

Metformin is available on prescription as tablets, as a liquid that you swallow and as sachets of powder that you dissolve in a drink.

Key facts

• Not everyone gets diabetes symptoms, so taking metformin may not make you feel any different. That does not mean it is not working, so keep on taking it.
• It's best to take metformin with a meal to reduce the side effects.
• The most common side effects are feeling and being sick, diarrhoea, stomach ache and loss of appetite. Vitamin B12 deficiency is also a common side effect of taking metformin in higher doses or for long periods.
• Metformin does not cause weight gain, unlike some other diabetes medicines.
• If you have diabetes, you can get free prescriptions for all of your medicines, not just your diabetes ones. You'll need to have a medical exemption certificate.