Diabetes affects about 1.4 million people in the UK. People with diabetes cannot control the level of sugar in their blood. There are two main types of diabetes. The symptoms of one type usually first appear in childhood, and can only be treated with regular injections of insulin. The second type usually only affects people over the age of 40, and can be treated by changing their diet. In later life, the condition may cause eye, nerve, kidney or heart problems.