Hyperglycaemia and pregnancy

Hyperglycaemia is caused by blood glucose levels rising too high.

This 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.

If you have type 1 diabetes you should also be given strips so you can check your ketone levels for yourself. Test you blood for ketones contact your diabetes team if you are unwell or your blood glucose levels remain too high. . 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 increase 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. There are no specific blood sugar levels given at which you should test because in pregnancy some women may have ketone 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 alright because you can roll along thinking you feel alright but actually you might not be 100 per cent, and if you’re not testing, you wouldn’t know." Sara, mum of two

Read about everyday management of type 1 or 2 diabetes in pregnancy


  1. Mayo Clinic. Hyperglycemia in diabetes.http://www.mayoclinic.org/diseases-conditions/hyperglycemia/basics/causes/con-20034795 
  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
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Read more about self-care in pregnancy with type 1 or 2 diabetes

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    Type 1 or 2 diabetes in pregnancy and diet and exercise

    Keeping your blood glucose levels within safe limits is a hugely important part of managing your diabetes, but you also need to think about your physical well-being.

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    Hypoglycaemia and pregnancy

    Hypoglycaemia happens when your blood glucose levels drop too low. This is more likely to happen if you treat your diabetes with insulin. If you treat your diabetes with diet or metformin alone, you are generally not at risk.

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    Hypos and hypers

    While you are pregnant, you will be at much higher risk of hypoglycaemia – especially in the early weeks. At the same time, you may not have your usual early warning signs (hypo unawareness), and the symptoms may be more severe than usual.

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    Type 1 or 2 diabetes and illness

    If you are ill with type 1 or 2 diabetes, more glucose is released into your bloodstream and your body becomes resistant to insulin.

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    Using insulin in pregnancy

    Whatever treatment you were using to control your diabetes before you became pregnant may change. If you were using tablets, you may have to start using insulin.

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    Testing your glucose levels

    Managing your blood glucose levels can be much harder after you become pregnant. As your body changes, so do your blood glucose levels.

More sections on type 1 or 2 diabetes in pregnancy

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