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Dealing with hyperglycaemia (high blood glucose)

This article provides information to help you understand the signs of experiencing a hyper, as well as some ideas for how you can try to prevent your blood glucose levels from getting above your optimal range. 

What does a hyper feel like?

The most common symptoms of experiencing a hyper include:

  • tiredness
  • passing more urine than usual (peeing more)
  • being very thirsty
  • blurred vision
  • headaches
  • feeling flushed

You may experience one or more of these symptoms when your blood glucose levels are high, or a family member or friend might mention that you do not quite seem your usual self. 

“My friends have been a real big help. Usually they’ll be able to tell when I am high or low, judging by the way I speak to them or the way I make decisions.”

-Jack and his mother, Sue, share their experiences on recognising when he is having a ‘hyper’

It may take a few days or weeks for the symptom(s) to develop while some people may not show any symptoms despite elevated blood glucose levels, specifically those who have had diabetes for a longer period.

As very high blood glucose levels can lead to serious complications, it is therefore very important to regularly check your blood glucose at home.

What to do if you experience hyperglycemia / high blood glucose (sugar)

What to do if you experience a hyper

  • Don’t panic
  • It is normal for your blood glucose level to go up and down in a day
  • Never miss your insulin injection(s)
  • If you have unusually high blood glucose readings or if you feel unwell, you should contact your nurse or doctor immediately
  • Test your blood or urine for ketones if you have been instructed to do so by your nurse or doctor

Emergency situations

Contact your nurse or doctor or dial 112/999 if:

  • You are vomiting and unable to hold down fluids
  • You have high blood glucose levels and ketones in your blood or urine

What are ketones?

Normally, with the help of insulin as a ‘key’, the body uses glucose from food to produce energy. When there is little or no insulin to allow the conversion of the glucose from food into energy, the body starts breaking down fat cells for energy. When this occurs, ‘ketones’ form in the blood and spill into the urine. These ketones can make you ill and if left untreated eventually lead to ‘diabetic ketoacidosis’ or DKA, a potentially life threatening condition.

How do you test for ketones?

You can test for ketones in the blood or urine. Several products are available for doing this - your nurse or doctor will advise you.

When should you test for ketones?

  • If your blood glucose level is over 15 mmol/L
  • When you are ill / vomiting
  • If you have taken extra insulin and your glucose level does not come down

Ketone levels can be checked in two different ways - in blood or in urine.


Novo Nordisk would like to thank the Diabetes Nurse Specialists and dietician who were instrumental in developing this content

What should you do if the ketone test is positive?

  • You will need additional insulin - call your nurse or doctor if you need advice
  • Ensure that you drink plenty of water or unsweetened fluids
  • Continue to test blood glucose levels and ketones every 1-2 hours until ketone free
  • Eat a small amount of carbohydrate if possible
  • Never stop taking your insulin


Date of preparation: December 2022. IE22DI00181

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