Hypoglycaemia (low blood sugar)

Hypoglycaemia, or a “hypo”, is an abnormally low level of glucose in your blood (less than four millimoles per litre).

When your glucose (sugar) level is too low, your body doesn’t have enough energy to carry out its activities.

Hypoglycaemia is most commonly associated with diabetes, and mainly occurs if someone with diabetes takes too much insulin, misses a meal or exercises too hard.

In rare cases, it’s possible for a person who doesn’t have diabetes to experience hypoglycaemia. It can be triggered by malnutrition, binge drinking or certain conditions, such as Addison’s disease.

Read more about the causes of hypoglycaemia

Symptoms

Most people will have some warning that their blood glucose levels are too low, which gives them time to correct them. Symptoms usually occur when blood sugar levels fall below four millimoles (mmol) per litre.

Typical early warning signs are feeling hungry, trembling or shakiness, and sweating. In more severe cases, you may also feel confused and have difficulty concentrating. In very severe cases, a person experiencing hypoglycaemia can lose consciousness.

It’s also possible for hypoglycaemia to occur during sleep, which can cause excess sweating, disturbed sleep, and feeling tired and confused upon waking.

Read more about the symptoms of hypoglycaemia


The symptoms of hypoglycaemia usually begin when your blood glucose level drops below four 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 regularly check your blood glucose levels.

Symptoms can vary from person to person, and it’s important to be aware of the early warning signs so you can treat them.

Signs and symptoms 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 your blood glucose levels drop low enough, you may become drowsy or even lose consciousness.

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

For some people, the warning symptoms become greatly reduced, putting them at significant risk of having severe episodes where they’re dependent on others for help.

Let your diabetes care team know if you develop this problem as your treatment may need to be changed to reduce the risk.

Read more about how hypoglycaemia is treated