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Hyperglycaemia occurs when there's a higher than normal level of glucose in the blood. It's generally found in people with diabetes.
Brought to you by NHS Choices



There are two types of diabetes: type 1 (insulin-dependent) and type 2 (non-insulin dependent).

Type 1 or insulin-dependent diabetes

In type 1 diabetes, the body produces little or no insulin. Insulin is a hormone that's released by the pancreas and helps the body to control its blood sugar level. If you have type 1 diabetes you'll require life-long treatment, and will need to check the level of sugar (glucose) in your blood regularly. The condition needs to be carefully monitored in order to prevent any complications from developing.

Type 2 or non-insulin dependent diabetes

In type 2 diabetes, the body does not make enough insulin, or cannot use insulin properly. This is called insulin resistance. This type of diabetes is usually linked to obesity. It is sometimes referred to as maturity onset diabetes because it occurs mostly in people over the age of 40.

Hyperglycaemia often only affects people with type 1 diabetes. If you have hyperglycaemia, it's normally easy to recognise the signs, and you can take appropriate steps to get it back to normal. This will usually involve adjusting the level of insulin (which is normally taken by people with type 1 diabetes) to control your condition.

If you have type 2 diabetes, you can manage your diabetes by carefully controlling your diet, or by using a combination of diet and tablets. There are some people with type 2 diabetes who also need to take insulin.


Symptoms of hyperglycaemia

Symptoms of hyperglycaemia are the same as those of untreated diabetes. They do not appear suddenly, but develop gradually, over a period of time. Symptoms include:

  • thirst,
  • frequent urination,
  • tiredness, and
  • increased susceptibility to infections, such as thrush.

If the symptoms of hyperglycaemia are prolonged, they may cause weight loss and blurred vision.

Weight loss is the result of your body trying to remove the excess glucose from your blood through your urine, causing your to lose calories.

High blood sugar can also changes the shape of the lenses in your eyes causing your vision to blur.

In the long term, hyperglycaemia can increase the likelihood of complications of diabetes, such as damage to your kidneys, eyes, and the nerves of the feet. The condition can also cause heart disease, circulation problems in your legs, and erectile problems (in men).


Causes of hyperglycaemia

An increase in blood glucose levels causes hyperglycaemia. The increase can be the result of:

  • emotional stress,
  • a change of medication,
  • a wrong (or missed dose) of insulin,
  • less exercise than usual,
  • a change in eating habits, or
  • an illness, such as a cold or throat infection.

Recent studies have shown that people taking the medications olanzapine and risperidone - which are sometimes used to treat schizophrenia and bipolar disorder - have an increased risk of developing hyperglycaemia and diabetes. If you are taking either of these medications, your GP should arrange for you to have regular blood sugar tests.


Diagnosing hyperglycaemia

The diagnosis of hyperglycaemia is based on the symptoms of the condition (which are the same as for untreated diabetes). They include thirst, frequent urination, tiredness and an increased susceptibility to infections, such as thrush.

If your GP suspects that you have hyperglycaemia, your blood glucose levels and the level of chemicals in your blood, such as potassium and sodium chloride (salt), may be tested.


Treating hyperglycaemia

If you have type 1 diabetes, you can be treated with insulin injections, as well as diet and exercise control. Your blood sugar levels will also all need to be closely monitored on a regular basis. A small portable instrument called a blood glucose meter can be used to check your blood sugar.

Type 1 diabetes

Usually, if you have type 1 diabetes, you will recognise the signs that your glucose level is high, such as extreme thirst, frequent urination and tiredness. Adjusting the levels of insulin in your blood, and drinking fluids, will help to bring your glucose levels down. You should contact your GP if your symptoms include nausea, vomiting, or drowsiness.

Type 2 diabetes

Hyperglycaemia is rare in people with type 2 diabetes but you can develop a condition called HONK (hyperosmolar non ketotic coma).

The loss of blood sugar causes your body to become extremely dehydrated and this causes you to fall into a coma (a state of unconsciousness).

If this happens, the person will need urgent hospital treatment for the dehydration, and to correct the levels of certain chemicals in their blood, such as glucose, potassium and sodium chloride (salt).

Hyperglycaemia can sometimes occur later in life (from middle-age onwards) in those who have not been diagnosed as being diabetic.


Preventing hyperglycaemia

If you have type 1 diabetes, in order to prevent hyperglycaemia from occurring, you will need to control your blood glucose levels by maintaining the right combination of diet and insulin injections (or tablets). Your GP will be able to provide you with information and advice about how you can do this.

It is important not to miss or alter your dose of insulin and to maintain your fluid and food intake. It is also important that you test your blood glucose levels regularly. Your GP will advise you when, and how often, you should test your glucose levels. If you have uncontrolled type 2 diabetes, or if it is difficult to control, you will be carefully monitored by the healthcare professionals who are looking after you.

Useful links

NHS Choices links

External links

This article was originally published by NHS Choices

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