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Whittington Health NHSUCL



1 2 1-glucose test

Key fact:
An important part of diabetes management is to keep your blood glucose as close to the normal range as you can every day.

What is hyperglycaemia?

Hyperglycaemia occurs when blood glucose levels become too high for a period of time, generally above 10 mmol/l (millimoles per litre), the top end of the normal range. Symptoms include dehydration, needing to pass urine frequently, and blurred vision. It can be triggered by a number of factors.

The aim of treatment is to keep your blood glucose level between 4-10mmol/l most of the time. This is good for your health and reduces the risk of symptoms from having low blood glucose levels (hypoglycaemia or 'hypo') or high blood glucose levels (hyperglycaemia).

Why might I have a high blood glucose level?

Contact your doctor's surgery or NHS 111 for advice if your blood glucose reading has been above 15mmol/l twice during a day, for two or more days in a row

High glucose levels can be triggered by:

  • an illness or infection
  • forgetting to take a tablet or not being on enough treatment
  • eating a meal with more carbohydrate than usual
  • starting a new medication that increases blood glucose levels, such as steroids or treatment for schizophrenia
  • a hypo, as the body tries to restore a normal blood glucose level.
Symptoms of high blood glucose:
  • feeling thirsty
  • having a dry mouth
  • needing to pass urine frequently
  • feeling tired or confused
  • blurred vision
  • losing weight in some cases.
You can check your blood glucose level by measuring it with a glucose meter.

What are the main effects?

Hyperglycaemia, if it is severe, can lead to loss of fluid or dehydration. If this is not treated, people can get very sick.

Will I develop hyperglycaemia?

Most of the time treatment works well. However, during an illness or a period of change, stress hormones can make the liver release extra glucose and this can lead to higher blood glucose levels.


More information about hyperglycaemia from NHS Choices.

See also above: Prevention | Checks & tests | Complications | Treatment