Hyperglycaemia (high blood glucose)

Type 2 diabetes develops when the pancreas (a large gland behind your stomach) is unable to produce enough insulin to control your blood glucose level, or when the body's cells don't respond properly to insulin that is produced.

Due to the lack of insulin or its inability to regulate blood glucose, your blood glucose levels may become very high.

Hyperglycaemia can occur for several reasons, including eating too much, being unwell and not taking enough diabetes therapy.

The main symptoms of diabetes are due to hyperglycaemia. They include:

• extreme thirst
• a dry mouth
• blurred vision
• drowsiness
• a need to pass urine frequently

Hyperglycaemia occurs when the body can't remove glucose (sugar) from the blood and turn it into energy. It usually only happens in people with diabetes.

The symptoms of hyperglycaemia are similar to untreated diabetes, and include:

• increased thirst
• the need to urinate frequently
• tiredness

Over time there may be further symptoms including weight loss and blurred vision.

Your GP will usually be able to diagnose hyperglycaemia based on a description of your symptoms. They may confirm the diagnosis by testing the level of glucose (sugar) in your blood.

What causes hyperglycaemia?

Hyperglycaemia is caused by an increase in blood glucose (sugar) levels. In people with diabetes, the body is unable to break glucose down into energy.

There are two types of diabetes, described below.

• Type 1 diabetes (insulin-dependent). The body produces little or no insulin. People with type 1 diabetes require lifelong treatment to replace the insulin. They also need to check their blood glucose level regularly to prevent complications developing.
• Type 2 diabetes (non-insulin dependent). In type 2 diabetes, either the body does not make enough insulin, or it cannot use the insulin properly (insulin resistance). This type of diabetes is often linked to obesity or being overweight and mostly occurs in people who are over 40 years of age.

Insulin is the hormone that helps remove glucose from the blood and converts it to energy.

If you have diabetes, you will be advised about how to manage your blood glucose levels. However, there are some situations that can trigger an increase in blood glucose, including:

• emotional stress
• a change of medication
• a wrong (or missed dose) of insulin
• changing your diet, or eating too much
• not exercising regularly
• an illness, such as a cold
• a side effect of certain medications

Preventing and treating hyperglycaemia

If you have diabetes, your diabetic care team will explain how to monitor and manage your blood glucose levels. If you have type 1 diabetes it is important not to miss or alter your dose of insulin and to maintain your fluid and food intake.

If hyperglycaemia occurs, your blood glucose levels will need to be lowered again. Increasing the dose of insulin is one way of doing this.

It is also important that you test your blood glucose levels regularly. Your GP will advise you about when and how often your blood should be tested.

If you have uncontrolled type 2 diabetes, or if it is difficult to control, you will be carefully monitored by the healthcare professionals looking after you.

When to see your GP

You should visit your GP if you or your child experiences the symptoms of hyperglycaemia, even if you haven’t been diagnosed with diabetes.

You should seek medical attention urgently if you start to experience any of the following symptoms as they may be a sign of diabetic ketoacidosis (where the body is unable to break down glucose):

• nausea or vomiting (feeling or being sick)
• stomach pain
• a fruity smell on your breath, which may smell like pear drops or nail varnish
• drowsiness or confusion
• hyperventilation (rapid breathing)
• dehydration (when the normal water content of your body is reduced, which can cause a headache, dry skin and a weak, rapid heartbeat)
• unconsciousness

Diabetic ketoacidosis is a serious condition that can be life-threatening and lead to coma (a sleep-like state where someone is unconscious for a long period of time).

If diabetic ketoacidosis is left untreated, there may be other serious complications such as long-term damage to blood vessels, nerves and organs.