There were more than 26 million metformin prescriptions dispensed in England alone in 2024
10:27, 15 Dec 2025Updated 11:06, 15 Dec 2025
Metformin is taken by millions of people
The NHS has issued a warning to people using a drug taken by millions of people. Record numbers of people are living with diabetes in the UK with latest figures showing more than 5.8 million people have the condition.
According to Diabetes UK almost 4.6 million people in the UK have been diagnosed with the health issue. However, it is believed there are almost 1.3 million people who could be living with Type 2 diabetes but have yet to be diagnosed.
And the number of people with the condition is rising. The figures, which are from 2023-24, are up by 185,034 from 2022-23.
Diabetes is a condition that causes your blood glucose (sugar) level to become too high. There are three common types.
Metformin is used to treat diabetes(Image: Getty)
Type 1 cannot be prevented and usually is discovered in childhood however Type 2 can sometimes be prevented by diet changes and gestational diabetes which happens in pregnancy.
While Type 1 diabetes means taking a medicine – insulin – for the rest of your life, many people with Type 2 or gestational diabetes can tackle the condition with lifestyle changes such as eating healthily, exercising and trying to lose weight, and sometimes medicines.
One of the most common drugs used to treat diabetes is metformin, with more than 26 million prescriptions dispensed last year in England alone. However the NHS says there are some important symptoms to watch for if you are taking the medication.
Posting on the NHS website it states there are six common side effects. These are:
feeling sickbeing sickdiarrhoeastomach acheloss of appetitemetallic taste in the mouth
There are also risks of B12 deficiency and can sometimes cause low blood sugar, usually if taking it alongside other diabetes medicines, such as insulin or gliclazide. However there are some side effects that are more serious.
On two occasions this means contacting your GP “straight away”. And another side-effect means dialling 999 “now”.
Serious side effects
The NHS says: “Serious side effects are rare and happen in less than 1 in 10,000 people. However you should call your doctor or dial 111 straight away if:
Diabetes is a condition that affects your blood glucose level(Image: SimpleImages via Getty Images)you get a general feeling of being unwell with severe tiredness, fast or shallow breathing, being cold and a slow heartbeatthe whites of your eyes turn yellow, or your skin turns yellow, although this may be less obvious on brown or black skin – this can be a sign of liver problems.”Serious allergic reaction
In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to metformin. The NHS says: “You should call 999 now if:
your lips, mouth, throat or tongue suddenly become swollenyou’re breathing very fast or struggling to breathe (you may become very wheezy or feel like you’re choking or gasping for air)your throat feels tight or you’re struggling to swallowyour skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)you suddenly become very confused, drowsy or dizzysomeone faints and cannot be woken upa child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
“You or the person who’s unwell may also have a rash that’s swollen, raised, itchy, blistered or peeling. These can be signs of a serious allergic reaction and may need immediate treatment in hospital.”