Tommy's PregnancyHub

Hyperglycaemia and pregnancy

Hyperglycaemia is caused by blood glucose levels rising too high.

Hyperglycaemia is a condition that is caused by blood sugar levels that are too high. It may happen:

  • if you have eaten more carbohydrate than your body can handle
  • if you have too little or miss a dose of your insulin or other diabetes medication,
  • if you are stressed or unwell – for example, if you have an infection or a high temperature
  • If you over-treat a hypo.

Symptoms of hyperglycaemia include weeing more frequently (especially at night), feeling especially thirsty, tired or lethargic, headaches, blurred vision and episodes of thrush. If blood glucose levels are slightly raised, you may not have any symptoms which is why it is important to check your blood glucose levels regularly. If blood glucose levels remain too high  (known as hypers) this can be dangerous. If left untreated over time, they can lead to diabetic ketoacidosis (DKA) – see below.

Read about hypoglycaemia in pregnancy

Diabetic ketoacidosis (DKA)

Diabetic ketoacidosis is a condition in which acidic chemicals called ketones build up in your body due to lack of insulin to use glucose for energy. Instead, your body tends to breakdown fat for energy, and ketone are produced as a by-product.. Symptoms may include

  • extreme thirst
  • extreme tiredness
  • blurred vision
  • tummy pain
  • nausea and vomiting
  • the smell of ketones (fruity, like pear drops) on your breath
  • unconsciousness.

Diabetic ketoacidosis is more common with people with type 1 diabetes, especially during pregnancy and can increase your risk of miscarriage – but it can usually be avoided if you are regularly testing and managing your blood glucose levels.

Test for ketones when your levels are high or if you become unwell

There are no specific blood sugar levels given at which you should test for ketones because in pregnancy some women may have ketones in your blood at lower blood glucose levels compared to people who are not pregnant. This is why the advice is to always test for ketones if your blood glucose levels are high or you become unwell.

The risk of ketoacidosis is another reason that it is so important that you go to all your appointments, so that if your blood glucose levels are not within the ideal range, you can work with your team to get them back under control.

"I did do a lot more blood testing to check that everything was OK. You can roll along thinking you feel alright but actually there might be a problem, and if you’re not testing, you wouldn’t know." 
Sara, mum of two

DKA with type 1 diabetes

If you have type 1 diabetes you should also be given strips so you can check your ketone levels for yourself. Test your blood for ketones and contact your diabetes team if you are unwell or your blood glucose levels remain too high.

DKA with type 2 diabetes

If you have Type 2 diabetes, you usually will not be given ketone testing kits when pregnant because DKA is generally uncommon in Type 2 diabetes. But as pregnancy increases the risk of DKA, if you are unwell at any time during your pregnancy or your blood glucose levels are too high, contact your healthcare team immediately and ask them to check your blood urgently for ketones. 

Read more

  1. Mayo Clinic. Hyperglycemia in diabetes. 
  2. NICE (2015) Diabetes in pregnancy: management of diabetes and its complications from preconception to the postnatal period, NICE guideline, National Institute for Health and Care Excellence
Review dates

Last reviewed: 1 September 2015
Next review: 1 September 2018