Hypoglycaemia (low blood sugar) - Symptoms 

Symptoms of hypoglycaemia 

The symptoms of hypoglycaemia usually begin when a person's blood glucose level drops to somewhere between 3 and 4 millimoles (mmol) per litre.

If you have diabetes, particularly if it's treated with insulin, you may be advised to use a small device called a blood glucose meter to check your blood glucose levels regularly.

The symptoms may vary from person to person and it is important to be aware of the early warning signs so that you can treat them.

Read more about how hypoglycaemia is treated.

Symptoms and signs of hypoglycaemia can include:

  • feeling hungry
  • sweating
  • dizziness
  • tiredness (fatigue)
  • blurred vision
  • trembling or shakiness
  • going pale
  • fast pulse or palpitations
  • tingling lips
  • irritability
  • difficulty concentrating
  • confusion
  • disorderly or irrational behaviour, which may be mistaken for drunkenness

If hypoglycaemia isn't treated promptly and blood glucose levels drop low enough, you may become drowsy or even lose consciousness.

Most people with insulin-treated diabetes notice that symptoms of hypoglycaemia change and become less obvious the longer they live with the condition.

Some people experience greatly reduced warning symptoms, putting them at significant risk of having severe episodes where they are dependent on others for help. It is important that people who develop this problem let their diabetes team know as their treatment may need to be changed to try to reduce this risk.

Hypoglycaemia while sleeping

Having a hypo while you're asleep is known as nocturnal hypoglycaemia. It is more common in people who treat diabetes with insulin.

Although some people find their sleep is disturbed when they experience nocturnal hypoglycaemia, you will often only notice the symptoms when you wake up in the morning. The symptoms can include:

  • headache, which is often likened to having a hangover
  • feeling unusually tired in the morning
  • damp sheets or clothing from sweating

Page last reviewed: 16/07/2013

Next review due: 16/07/2015

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Healthy living with diabetes

Diabetes can have serious health consequences, including heart disease and blindness. But with careful management you can reduce your risk