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Whittington Health NHSUCL

Hypoglycaemia (hypos)


Man sweating while experencing a hypo

Key fact:
If you find you are prone to hypos, carry your meter and some glucose tablets or other fast-acting carbohydrate with you all the time.

Why do hypos happen in diabetes?

Hypos occur when blood glucose levels become too low, generally below 4mmol/l. Symptoms include sweating and feeling weak or dizzy. They happen in people who take certain medicines, like gliclazide or insulin, that lower blood glucose.

How will I know I am having a hypo?
  • sweating
  • hunger
  • tingling lips
  • having a fast heart rate
  • headache or blurred vision
  • feeling shaky,weak or trembling
  • feeling anxious
  • lack of concentration and confusion
  • dizziness
  • change of behaviour and irritability
  • measuring the blood glucose level.

Read about treatment

A hypo may be triggered by:

  • eating less than usual or skipping a meal
  • exercising more vigorously than usual
  • starting or increasing medicines like gliclazide or insulin
  • a bigger than expected effect of medication after losing a lot of weight
  • having more alcohol than usual or drinking alcohol on an empty stomach.

Most people get warning signs of a hypo. However, hypos can happen during sleep when they are harder to notice. If people have frequent hypos, they can get less of a warning.

What are the main problems?

Hypos can lead to reduced awareness and sometimes cause people to pass out. If you are alone, driving or operating machinery, this can be dangerous. This is why it is important to recognise the symptoms so you can act quickly to restore a normal blood glucose level.

Will I have hypos?

The aim of treatment in diabetes is to keep your blood glucose level between 4 and 10mmol/l most of the time.

It may be helpful to understand how your medication affects your glucose levels so you can reduce the risk of developing problems. To find out more about your medication, visit the medicines section of this website.

If you are prone to hypos, being prepared makes a big difference. Always carry your blood glucose meter and some fast-acting carbohydrate such as a glucose tablet.

Click on the image below to watch a video of Philip describing how he feels when his blood glucose levels are low.

From other websites

 Information about hypos from Diabetes UK.

Information about hypos and driving from Diabetes UK.

Videos and information from Health Talk Online.

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