6 Genes and risk
Approximately 150 million people worldwide have diabetes, of which 90 per cent have Type 2 diabetes. The incidence of the condition is rapidly increasing. In western countries about 10 per cent of people over the age of 65 years have diabetes. In the UK it is thought that there are between 765 000 and 1 million people with undiagnosed Type 2 diabetes, that is, 29–36 per cent of the total with diabetes (Watkins, 2003). These undiagnosed numbers are based on population samples where everyone is screened using a variety of health tests including those that diagnose diabetes.