Taking medication and insulin for gestational diabetes

Some people need tablets or injections to help manage their blood sugar levels, if diet and exercise alone are not enough.

If you have gestational diabetes, you can reduce the risk of problems during your pregnancy by not gaining too much weight and keeping your blood sugar (glucose) levels in the ideal range

While many people can do this by making changes to their diet and exercise routine, other people do need tablets or insulin injections.

You’ll likely be offered medication if you’ve tried changing your diet and being more active for 1-2 weeks, but your blood sugar is still too high. Some people are offered medication as soon as they’re diagnosed with gestational diabetes.

Your healthcare team will talk to you about the best gestational diabetes treatment for you.

You will need to keep sticking to a healthy diet and doing plenty of exercise, even if you’re using medication.  

"If I’d understood more about it, I’d have stuck with the diet and found ways to lower my glucose levels. Having insulin is not just a quick fix so that you can eat what you want." 


Metformin tablets

Metformin is taken as a tablet. It tends to be the first type of medication that people with gestational diabetes try. It makes your body respond better to insulin, which is the hormone that lowers the amount of sugar in your blood. 

There are some common side effects of metformin. These can include:

  • feeling sick
  • being sick
  • stomach cramps
  • diarrhoea
  • loss of appetite.

Starting on a low dose (just 1 tablet at a time) and upping the dose slowly should reduce these side effects. Taking the tablet with or after meals can also help. Talk to your healthcare team if you have any concerns.

Insulin injections

Most people will try diet and exercise changes first, followed by metformin tablets if their blood sugar still isn’t low enough. You may be offered insulin if:

  • you can’t take metformin or it causes side effects
  • metformin is not lowering your blood sugar enough, even when you’re taking a full dose.

Some people are offered insulin – sometimes with metformin – as soon as they are diagnosed with gestational diabetes. 

This may happen if: 

  • your blood sugar level before breakfast (‘fasting’ blood sugar level) is very high
  • your baby is very large (macrosomia) or there is too much amniotic fluid around them (polyhydramnios).

Insulin is taken as injections. Your diabetes team will show you how to do these yourself. They’ll also tell you:

  • when to inject yourself (for example, when you wake up, at bedtime or before meals)
  • where to keep your insulin
  • where to put used needles.

Try not to worry if you don’t like needles. Insulin injections are not like some injections that you may have had in the past. The device is like a pen, with a very thin needle. It should only hurt a little, if at all. Also, insulin is injected just under the skin, rather than into a muscle. This means the needle doesn’t go in very far.

Find out more about injecting insulin for gestational diabetes.

"It’s amazing, the needle itself is tiny. It was straightforward, though you always have to find somewhere to do it – a loo or something." 


Hypoglycaemia (low blood sugar) if you're on insulin

Insulin can sometimes cause the level of sugar in your blood to fall too low. This is called hypoglycaemia (a ‘hypo’ for short). Your healthcare team will explain how to treat this in case it happens.

Find out more about hypoglycaemia and how to treat it.

Driving if you’re on insulin

If you’re using insulin for your gestational diabetes, you will need to check the rules from the Driver and Vehicle Licensing Agency (DVLA) in England, Scotland and Wales, and the Driver and Vehicle Agency (DVA) in Northern Ireland

You may also need to tell your car insurance provider.

This is because insulin use can cause problems with low blood sugar, making you less able to concentrate and react quickly. If you’re taking metformin alone, it is very unlikely to cause problems with low blood sugar.

After your baby is born

You’ll most likely be advised to stop your diabetes medication as soon as your baby is born. This is because gestational diabetes usually goes away after the birth.

Find out about how diet and exercise can also help to keep your blood sugar levels under control.

Royal College of Obstetricians & Gynaecologists, Diabetes UK (2021). Gestational diabetes - Information for you. Available at: https://www.rcog.org.uk/media/b10mqyfw/pi-gestational-diabetes.pdf (Accessed January 2024) (Page last reviewed 09/2021)

National Institute for Health and Care Excellence (2020). Diabetes in pregnancy: management from preconception to the postnatal period. NICE guideline 3. Available at: https://www.nice.org.uk/guidance/ng3 (Accessed January 2024) (Page last reviewed 16/12/2020)

Electronic Medicines Compendium (2023). Metformin 500 mg film coated Tablets - Summary of Product Characteristics. Available at: https://www.medicines.org.uk/emc/product/10759/smpc (Accessed January 2024) (Page last reviewed 29/09/2023)

Electronic Medicines Compendium (2021). Lantus SoloStar 100 units/ml solution for injection in a pre-filled pen - Summary of Product Characteristics.  Available at: https://www.medicines.org.uk/emc/product/8098/smpc (Accessed January 2024) (Page last reviewed 30/04/2021)

Review dates
Reviewed: 05 March 2024
Next review: 05 March 2027