Metformin

Metformin is a medicine used to treat Type 2 diabetes and Gestational (pregnancy) diabetes. It is only available as an oral tablet.

Metformin works by:

• reducing the amount of sugar or glucose the liver releases into your body
• helping the insulin your body makes to 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, so your blood sugar levels can become too high. This can happen in pregnancy for some women with risk factors (NICE guideline Section 1.2.2)

It's usually prescribed for diabetes when diet and exercise alone have not been enough to control your blood sugar levels. Starting metformin isn't a sign of failing to manage your diabetes and at first, it might seem like a big step to take diabetes medication but taking it can help you to manage your diabetes and reduce diabetes complications. The effects of pregnancy hormones increase blood sugar, especially in the 3^rd trimester (24 weeks onwards). Women who have been managing well on diet only may need Metformin as an additional treatment to control blood sugar.

If you have Gestational diabetes, Metformin is usually discontinued once you have delivered your baby. If you have Type 2 diabetes and you were not on Metformin prior to your pregnancy, it is likely that you will be advised to discontinue it after pregnancy.

Who can take it?

Metformin can be taken by adults and children aged over 10 years. It is also safe to take during pregnancy, either alone or combined with insulin.

Metformin may not be suitable for some people if they have had an allergic reaction to metformin or have liver or kidney problems. This can be discussed at your appointment by a Specialist Midwife or Consultant.

You may need to stop taking metformin before having surgery and certain medical tests. Please discuss your medications with your team prior to any tests or surgery.

How and when to take it

Metformin comes in two different types of tablets: standard-release tablets and slow-release tablets.

Standard tablets are routinely prescribed and release metformin into your body quickly.

Slow-release tablets work gradually and are usually prescribed if you are suffering from any side effects when taking the standard-release tablets.

Metformin tablets come in different strengths.

The maximum daily dose is 2000mg a day. This can be taken as four 500mg tablets a day or two 1000mg tablets a day. Metformin is often started at a low dose and built up over a few weeks to reduce the chances of side effects and allow the body to get used to it.

You should take your metformin tablets whole with a drink of water with or just after your meal to reduce the chance of getting side effects.

If you miss a dose of metformin, skip the missed dose and take the next dose at the usual time. Do not take 2 doses to make up for a forgotten dose. If you often forget doses, it may help to set an alarm to remind you.

Taking too much metformin can cause serious side effects. Please contact 111 for urgent advice if you have taken more than the recommended dose.

Side effects

The most common side effects are feeling and being sick, diarrhoea, stomach ache and loss of appetite. Most women find that these are usually mild and pass after a few days.

Metformin does not cause hypoglycaemia (abnormally low blood sugar).

Metformin does not cause weight gain, unlike some other diabetes medicines.

Metformin and breastfeeding

If your doctor or midwife says your baby is healthy, you can take metformin whilst breastfeeding.

Metformin passes into breast milk in non-significant amounts and has not been linked with side effects in any breastfed babies. It has been deemed safe for breastfeeding.