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Metformin and diabetes

Metformin is a medication that helps the insulin you produce work better. You usually take it as a tablet. 

Metformin is the most common treatment for type 2 diabetes. You might also take it if you have gestational diabetes.

Starting metformin isn't a sign of failing to manage your diabetes. In fact, it will help you get on top of your diabetes and start managing it with greater confidence.

So while at first it might seem like a big step to take medication, you'll soon find that it doesn't have to run your life. It will also give you the best chance of avoiding complications associated with type 2 diabetes. Over time you might even be able to stop taking it if your type 2 can be moved into remission

If you do have gestational diabetes, metformin is safe to take when you're pregnant or breastfeeding.

Getting started

The first time you get your metformin prescription there will be a lot going through your mind. For starters moving onto medication will be a big life change for you. 

You might find that taking metformin is overwhelming when you start. Unlike most prescriptions, you won't have an end date. You'll also have side effects to think about which can be a real challenge. But it's important that you don't stop taking your medicine without speaking to your doctor first. 

And remember that you have a healthcare team who can support you. Or you can speak to someone from our helpline where you can get support over the phone and on our live chat. Looking after how you feel is an important part of managing your diabetes, so don't feel like you have to go through it alone. 

As someone living with diabetes, you don't pay for prescriptions on the NHS in England. So make sure you don't get charged for your metformin. Prescriptions are free for everybody in the rest of the UK.

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What does metformin do?

When it comes to treating your diabetes, metformin will work by:

  • reducing the amount of glucose (sugar) the liver releases into the body
  • helping the body's insulin work better.

This means that metformin improves your insulin resistance so that the insulin you produce works better. Insulin resistance is when your insulin doesn't work properly and can increase your blood sugar levels. 

Metformin also has other uses. One of those is helping to reduce the risk of heart disease, which can be a serious complication of diabetes. 

Different types of metformin

When you get your prescription you might notice that it has a different name. That's because there are many different brands out there that provide the drug metformin. But the important thing for you to know is that the medication you've been given is metformin. Speak to your doctor if you have any questions. 

Metformin comes in the following brands:

  • Bolamyn
  • Diagment
  • Glucient
  • Glucophage
  • Metabet.

You can also be given metformin in combination with other diabetes medication all in the same tablet. This is because on its own it doesn't always work and so needs support from other medicines. 

Diabetes medication often exists in groups or families depending on how they work. Metformin is part of the biguanide family and it's the only type of diabetes medication in this group. 

Metformin is the most common treatment for type 2 diabetes

Your prescription

Your metformin prescription can be slow or standard release tablets. They do similar jobs but in different ways. Your doctor should explain your prescription to you but it's important to make sure you ask if you don't feel you know enough. 

It's also possible to get it as a liquid if you struggle to swallow tablets. Speak to your doctor if this is something you need. 

And make sure you talk to your GP or your diabetes team if you struggle to take your metformin. They might be able to help by giving you a different dose. 

Standard-release tablets

Standard-release tablets will give your body medicine quickly. Because they act faster, you may need to take more of them more often, depending on your dose.

You can also crush your standard-release tablets and add them to your food. But you can't do that with slow-release tablets. 

Slow-release tablets

Slow-release tablets dissolve slowly. This means that the dose you take will be lower, usually only one a day. You'll be prescribed slow-release tablets if you're not reacting well to standard-release tablets. That's because slow-release tablets have fewer side effects, so you should react better to them. 

Metformin side effects

Like all medicines, metformin has side effects for some people. These side effects usually settle down once your body gets used to the medicine. You might want to start taking your medication at the weekend or during a break from work. That's because if you do feel any side effects then you can deal with them in your own time and without added pressure.

Check the patient information leaflet that comes with your medicine for more information. But here are some of the common side effects you should be aware of.

Feeling sick, being sick or having diarrhoea

If you feel sick after taking your metformin then try taking it with food. It's best to take it with food even if you don't have this side effect anyway. If you continue to feel sick then you might need to have your dose changed. Speak with your doctor about how you're feeling to get an idea of what you can do.

If you're being sick or have diarrhoea, then take lots of small sips of water. It’s important that you keep drinking lots of water or squash to avoid dehydration. And if you have any signs of dehydration then speak to your doctor or pharmacist. If you have any signs of sickness or diarrhoea then your doctor might be able to prescribe sickness tablets. But it's also important that you don't take any sickness or diarrhoea tablets without speaking to someone first. 

The signs look out for are:

  • Being really thirsty.
  • Dry mouth, lips and eyes.
  • Feeling more tired than usual.
  • Going to the toilet less than four times a day.
  • Dark yellow and strong-smelling pee.
  • Feeling light headed.

You shouldn't stop taking your medication if you’re feeling or being sick. Always speak to your doctor before making changes to your medication.

Stomach ache or no appetite

If you have stomach pain or no appetite, you should eat smaller meals more regularly. If you do have stomach pain you can use things like a hot water bottle or heat pads to help you.

Metallic taste in the mouth

You can also have a metallic taste in your mouth as a result of the metformin. Some people find chewing sugar-free gum gets rid of this taste.

Longer term side effect – Low vitamin B12 levels   

Long term use of metformin, particularly for people on higher doses, can lead to lower levels of a nutrient called Vitamin B12. This vitamin helps to keep red blood cells and nerves healthy.  You should speak to your doctor, who will arrange a blood test, if you begin to feel new or much worse extreme tiredness. Or pins and needles, a red and sore tongue, or pale or yellow skin. You should continue to take metformin while you wait for this test. 

Can you stop taking metformin?

Don’t stop taking your metformin unless your doctor recommends you do.

Starting a long-term prescription can be challenging and you might feel like you want to stop taking your tablets, but this isn’t a good idea. If you do feel overwhelmed by your medication then try talking to someone. Our helpline can support you with information and advice. And our forum is also a great place to meet people who are going through or have been through similar things that you’re dealing with. 

Coming off medication in diabetes remission

Some people are able to stop taking diabetes medication like metformin, by putting their diabetes into remission. This means that blood sugar levels are in the non-diabetes range without needing any medication. There are many ways people with diabetes have done this, but they mostly involve making changes to your diet and losing weight.

It’s important to remember that this isn’t an option for everyone and isn’t an easy thing to do. If you’re thinking of making changes to your diet, it’s a good idea to speak to your healthcare team first.

We’ve got lots of information about diabetes remission so you can get all the facts.

Jon was diagnosed with type 2 in 2013 and was given metformin. But after learning more about his condition, Jon started to address his weight. After a couple of months, he was able to gradually stop taking medication. 


“Realising I had to address my weight, I started swimming every day and walking as much as 

possible… Within two months, I'd lost nearly 4 stone, my sugars had gone back to pre-diabetes levels and I was able to gradually stop taking metformin.”

Jon was diagnosed with type 2 diabetes in 2013

How does metformin affect your weight?

You may have heard that metformin can help you lose weight. But there isn't a straight answer to whether it can. 

There have been studies on its effects on weight loss. But currently, it hasn't been approved for weight loss. That's because the makers of the drugs haven't put it forward for the research.

That means metformin isn't labelled as safe to use for weight loss. And although some people think that it makes you gain weight, putting on weight isn't a side-effect of metformin. 

Metformin’s other uses

While metformin is a drug that is used to treat diabetes, it can also be prescribed for other uses. Women with polycystic ovary syndrome (PCOS) may be given metformin, but it’s not currently licensed for PCOS. That's because it can lower insulin and blood sugar levels. This helps women with PCOS with their ovulation and periods. It also lowers the risk of a miscarriage. Speak to your doctor if you want to know more about PCOS and metformin. 

If you have type 1 diabetes then you might also start metformin, but only if you have insulin resistance. 

Metformin can also have other long-term health benefits. These include lowering cholesterol levels and reducing heart disease risk. 

There is also research taking place into what else metformin can be used for. This includes as a drug to prevent cancer. But these studies have not found any evidence yet.


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