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Diabetes explained

This leaflet explains what diabetes is. It also explains the difference between Type 1 diabetes and Type 2 diabetes.



What is diabetes and what causes it?

Diabetes mellitus, usually known simply as diabetes, is a common health condition. Diabetes is caused when the amount of glucose (sugar) in the blood is too high because the body is not able to convert glucose into energy properly.

Our body creates glucose when we digest starchy foods such as bread, rice, potatoes, chapatis, yams and plantain. We also get glucose from sugar and other sweet foods.

Normally, the pancreas (a gland near our stomach) releases a hormone called insulin. Insulin allows the glucose to enter our cells where it is converted into fuel for energy. When you have diabetes, your body does not make insulin, or does not make enough of it, and so the glucose cannot get into your cells to be turned into energy. This makes you feel tired and ill.

Almost 4 million people in the UK have been diagnosed with diabetes, that is about 6 in every 100 people. This figure rises to over 5 million if we include people who have diabetes but have not yet been diagnosed and are unaware they have the condition.

What are the symptoms of diabetes?

The main symptoms of untreated diabetes are increased thirst, going to the toilet all the time (especially at night), extreme tiredness, weight loss, genital itching or regular episodes of thrush, and blurred vision.

The two main types of diabetes

  • Type 1 diabetes
  • Type 2 diabetes (nine out of ten people with diabetes have type 2)

Type 1 diabetes develops if the body is unable to produce any insulin. This type of diabetes usually appears before the age of 40. It is treated with insulin injections and diet, and regular exercise is recommended.

Type 1 diabetes develops when the cells in the pancreas that produce insulin have been destroyed. Nobody knows for sure why this happens but damage to the cells is most likely an abnormal reaction of the immune system that may be caused by a virus or other infection. Type 1 diabetes sometimes runs in families. This type of diabetes generally affects younger people.

Type 2 diabetes used to be called ‘maturity onset’ diabetes because it usually appears in middle-aged or elderly people, although nowadays it is increasingly affecting younger people.

Type 2 diabetes develops when the body can still make some insulin, but not enough, or when the insulin that is produced does not work properly. This is known as insulin resistance. This type of diabetes usually appears in people over the age of 40, though it can appear in younger people.

People who are overweight are particularly likely to develop type 2 diabetes. It tends to run in families and is more common in South Asian and African-Caribbean communities, where it usually appears in people over the age of 25.

Type 2 diabetes is treated in one of three ways:

  • diet and exercise
  • diet, exercise and tablets
  • diet, exercise and injections such as insulin

The main aim of treatment of both types of diabetes is to maintain blood glucose and blood pressure levels as near to normal as possible.

This, together with a healthy lifestyle, will help to improve well-being and protect against long-term damage to the eyes, kidneys, nerves, heart and major arteries.

Some people wrongly describe type 2 diabetes as ‘mild’ diabetes. There is no such thing as mild diabetes. All diabetes should be taken seriously, monitored regularly and treated properly. Diabetes UK has a free Know your risk? calculator which can help you work out your risk of developing type 2 diabetes.

Other causes of diabetes

There are some other, much rarer causes of diabetes. These include:

Other rare cause of diabetes include:

  • disorders of the pancreas gland such as chronic pancreatitis
  • drugs such as steroids
  • other conditions such as cystic fibrosis or an endocrine condition like Cushing syndrome


Useful resources

This video gives a good explanation of what causes diabetes. For more information on type 2 diabetes, see Type 2 diabetes.

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