Diabetes Dr Trisha Macnair Dr Rob Hicks There are two main types of diabetes, which affect more than two million people in the UK.

In this article

What is it? What causes it?

What are the symptoms? How is it diagnosed?

Who's affected? What's the treatment?

Diabetes mellitus occurs when the pancreas doesn't make enough or any of the hormone insulin, which is needed to regulate the level of glucose (sugar) in the blood.

Glucose is the main source of energy for all cells in the body. Insulin stimulates these cells to absorb the glucose they need from the blood.

It also stimulates the liver to absorb and store any insulin that's left over. In diabetes, the level of glucose in the blood is too high.

There are two main types of diabetes:

• Type 1 diabetes - usually starts in childhood or young adulthood and is caused by a severe lack of insulin (because most of the cells that produce it in the pancreas have been destroyed)
• Type 2 diabetes - usually starts after the age of 40 and develops when the body can't produce enough insulin or when the insulin produced doesn't work properly

Apart from a few rare types of diabetes, it's a polygenic condition - genetic susceptibility depends on inheriting several abnormal genes.

Other factors, such as being overweight and physically inactive, also increase the risk. Type 2 diabetes mostly results as these genetic influences take effect over time.

In 90 per cent of type 1 diabetes, there's no family history of the disease. It may be that an event, such as an infection, can trigger the genes that lead to the condition.

In type 1 diabetes, people often develop symptoms over a short period of time, usually weeks or months. They feel tired, thirsty all the time, need to urinate a lot and may lose weight.

Itching of the genitals or regular episodes of thrush or blurred vision may also occur.

In type 2 diabetes, symptoms develop slowly or there might not be any symptoms at all.

When blood sugar levels become very high, there's a risk of coma and death.

Diabetes that isn't controlled can cause many serious long-term problems. Excess glucose in the blood can damage the blood vessels, contributing to heart disease, strokes, kidney disease, impotence and nerve damage.

Uncontrolled diabetes is the most common cause of blindness in people of working age. People with diabetes are also 15 per cent more likely to have an amputation than people without the condition.

In most cases, it's possible to reduce the risk of such complications by following medical advice and keeping diabetes under control. It's vitally important for people with diabetes to check their glucose levels regularly at home and to attend hospital check-ups, so any problems can be detected and treated early.

Diabetes may be detected during a routine urine test when excess glucose is present.

When symptoms have drawn attention to the problem, a blood test will confirm whether or not the underlying cause is diabetes.

Antenatal screening is not possible.

More than two million people in the UK have been diagnosed with diabetes. It's estimated that a further 750,000 have the condition without being aware of it.

Those at risk include:

• People over 40, or over 25 and African-Caribbean, Asian or from a minority ethnic group
• People with a close family member who has type 2 diabetes
• People who are overweight or who have a large waist size
• Women with polycystic ovary syndrome who are overweight
• Women who've had diabetes in pregnancy (gestational diabetes)

The first step in the treatment of diabetes is to eliminate the symptoms. The next step is to prevent the physical harm it can cause.

Although no cure exists for type 1 diabetes, its symptoms can be eliminated by adhering to a healthy diet that has a controlled amount of sugar in it, and by having regular injections of insulin to replace that which the body is not providing. This aims to keep the blood glucose level steady.

Insulin can't be taken by mouth because digestive juices and enzymes destroy it before it can get into the bloodstream. Scientists are working on ways of overcoming this.

Most people find giving themselves the injections simple and painless, as the needle is so fine. How often someone needs to inject insulin depends on what their diabetes specialist has recommended and which type of insulin they're using.

Insulin can be short-acting, medium-acting or long-acting. Some people need it twice a day, some three times a day and some use an insulin pen to give themselves insulin just before meals.

Devices are becoming available that deliver insulin continuously under the skin in response to need. Inhaled insulin is also available.

Self-help

• Monitor blood glucose levels
• Attend hospital check-ups
• Have regular eye checks
• Inform the DVLA
• Wear a medi-alert bracelet
• Always have some sugar available

Many people with type 2 diabetes need only to eat a healthy diet to control their diabetes. If this isn't enough, medication or insulin may be necessary.

Everyone with diabetes should eat a diet that's low in fat, sugar and salt.

Regular exercise, not smoking and keeping to an ideal weight also help prevent the complications of diabetes, such as heart disease. Keeping blood pressure at a safe level is important.

People with type 1 diabetes are allowed to drive, but must inform the DVLA that they have diabetes. If blood sugar goes too low, they may develop hypoglycaemia.

Most wear an identity bracelet to inform people they have diabetes in case they black out and need help.

Fortunately, diabetes can be managed well, so people can live a normal lifestyle.

This article was last medically reviewed by Dr Rob Hicks in January 2008