Both type 1 and type 2 diabetes occur when your body doesn't produce enough insulin (the hormone that allows glucose to convert to energy.) In type 1 diabetes, the body stops producing insulin when the cells that produce are destroyed, causing a build-up of glucose in the body. The insulin-producing cells may be destroyed by a virus or other infection, but research into the causes is still going on. This type of diabetes usually comes on quite suddenly, usually occurs in younger people and is always treated with insulin, along with a carefully balanced diet and healthy lifestyle.

Type 2 is caused by not enough insulin being produced, rather than the cells being destroyed altogether. This type can start more gradually, takes longer to diagnose and people often (though certainly not always) develop it later in life. Lifestyle and diet changes play a big part in treating this form of diabetes.