Diabetes: risk factors

The risk factors for diabetes are different for type 1 diabetes and type 2 diabetes.

The cause of type 1 diabetes is not well understood. Autoimmune mechanisms (the development of antibodies directed at the body's own tissues) may lead to the destruction of the beta cells in the pancreas that produce insulin. It has been suggested that infectious agents may play a role, though no specific organism has been identified. Type 1 diabetes is more common in the families of people with type 1 diabetes, and genetic factors probably play an important role.

Type 2 diabetes becomes much more common with increasing age, although it may also occur in young people. Overweight and obesity are also important risk factors: the risk of type 2 diabetes is around ten times higher among those with a body mass index (BMI)* over 30 compared with those with a BMI under 30. Type 2 diabetes is more common in the families of those with type 2 diabetes, and a number of genetic markers of increased risk have been identified. Type 2 diabetes is more common in people from some ethnic groups including people with African, Asian and Caribbean backgrounds, compared with European populations.

* Body mass index (BMI) is a measure of obesity, calculated as a person's weight in kilograms divided by the square of their height in metres (kg/m2). Waist circumference has been proposed as a more useful measure of central obesity, which is also linked with the risk of type 2 diabetes.