This leaflet is designed for people taking Metformin for type 2 diabetes.
What does this medication do?
Metformin works to lower blood sugar levels. It does this in several ways. It reduces the
amount of sugar released by the liver, it reduces the amount of sugar absorbed by the intestine and it increases the sensitivity of the body to insulin, so helps insulin to work
more effectively. Metformin has been shown to reduce the risk of certain complications of
diabetes such as heart disease and stroke. It can also help to maintain a stable weight or
in some cases promote weight loss.
How do I take this medication?
It is best to take Metformin with a meal. Usually, you will be asked to start by taking one
tablet with your main meal of the day; this dose will then be gradually increased over a few weeks. If you are taking a slow or modified release form of Metformin you can take your tablets once a day, otherwise you may be asked to take them twice or three times a day.
Who can’t take this medication?
Metformin may not be suitable for certain people. This medication is not suitable if you
have poor kidney function.
Your prescriber will review your kidney function when prescribing metformin to check it is
suitable for you.
What are the common side effects?
Many people experience no side effects taking Metformin. However, like all medicines,
Metformin can cause side effects.
Some people feel nauseous or experience diarrhoea when they first start taking Metformin. This generally improves over a few weeks and is the reason why the dose is gradually built up. If you continue to experience diarrhoea you may be switched onto a slow-release version of the medication.
Taking Metformin can cause vitamin B12 deficiency. Signs of this are feeling very tired, muscle weakness, sore or red tongue, mouth ulcers, vision problems, pale or yellow skin. If you experience any of these symptoms whilst taking Metformin please contact your GP. Your doctor can check your vitamin B12 levels and if they are low can provide treatment for this.
Metformin does not usually cause hypoglycaemia (low blood sugars) when taken on its own.
Do I need to be monitored?
You do not need to test your own blood sugars when taking Metformin unless you are also taking other diabetes medications. Your healthcare team can advise you on this.
Your doctor will monitor your kidney function whilst you are on this medication.
Are there any sick day rules?
If you have an illness that causes you to become dehydrated such as vomiting or diarrhoea you should temporarily stop your Metformin. You can restart your Metformin 48 hours after illness if you are eating and drinking fluids normally again. There are no risks from temporarily not taking your Metformin.
You may also be asked to temporarily stop your Metformin if you have certain types of
What about driving?
Certain people with diabetes need to inform the Driver and Vehicle Licensing Agency
(DVLA). This depends on your medication regimen, whether you hold a group 1 or group
2 licence and other individualised factors.
Full advice can be found via the DVLA website or https://www.gov.uk/diabetes-driving
If you have any queries about this medication, contact your diabetes team, GP or pharmacist.