Type 1 diabetes develops when the insulin-producing cells in the body have been destroyed and the body is unable to produce any insulin.

Insulin is the key that unlocks the door to the body’s cells. Once the door is unlocked glucose can enter the cells where it is used as fuel. In Type 1 diabetes the body is unable to produce any insulin so there is no key to unlock the door and the glucose builds up in the blood.

Nobody knows for sure why these insulin-producing cells have been destroyed but the most likely cause is the body having an abnormal reaction to the cells. This may be triggered by a virus or other infection. Type 1 diabetes can develop at any age but usually appears before the age of 40, and especially in childhood.

Type 1 diabetes accounts for between 5 and 15 per cent of all people with diabetes and is treated by daily insulin injections, a healthy diet and regular physical activity.

Reviewed January 2009
Next review June 2010