An abnormally low level of glucose in the blood, depriving body cells of glucose

  • Age, gender, genetics, and lifestyle as risk factors depend on the cause

In hypoglycaemia, the body’s cells are deprived of glucose, which is their main source of energy. As a result, symptoms such as sweating, nausea, and hunger develop. The condition is usually temporary, and occurs most often as a side effect of insulin treatment for type 1 diabetes (see Diabetes mellitus). It is less common in people with type 2 diabetes and is rare in those who do not have diabetes; faintness or nausea that are sometimes attributed to hypoglycaemia are in fact usually due to other disorders, tiredness, or stress.

What are the causes?

In people with type 1 diabetes, hypoglycaemia is usually due to a dose of insulin that is excessive in relation to food intake and lowers the blood glucose level too much. The insulin dosage must be balanced with food intake, which raises blood glucose levels, and physical activity, which lowers blood glucose. If the balance is disturbed and the glucose level falls, hypoglycaemia may result.

Hypoglycaemia in people with type 2 diabetes and impaired kidney function may be due to the gradual build-up of glucose-lowering drugs in the blood (see Drugs for diabetes mellitus).

The rare cases in people without diabetes are usually due to serious medical problems, such as severe liver disease, adrenal failure, or very rarely an insulin-secreting tumour of the pancreas. In babies, especially newborns, hypoglycaemia may occur because the liver does not yet have sufficient stores of glucose.

What are the symptoms?

When blood glucose levels become low, warning signs of hypoglycaemia may rapidly develop, including:

  • Sweating, nausea, hunger, and anxiety.

  • Rapid, forceful heartbeat.

If blood glucose continues to fall, further symptoms may develop, including:

  • Confusion.

  • Slurred speech and unsteady movements, similar to drunkenness.

  • Seizures (particularly in children).

Unconsciousness may result. If not treated promptly, the condition may cause permanent brain damage or death.

What is the treatment?

If you have diabetes mellitus and experience the above symptoms, take food or drink that contains sugar immediately. Always carry sweets or biscuits with you and wear an information tag to inform people that you have diabetes. If you develop hypoglycaemia and lose consciousness, you will need an immediate injection of glucagon, a hormone that restores consciousness by raising blood glucose levels. If the treatment fails or is not available, you will need emergency treatment with intravenous glucose.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

Back to top