Type 1 diabetes is the result of an autoimmune process in which the body's immune system attacks and destroys the insulin producing cells of the pancreas. The cause of type 1 diabetes is unknown, but it is believed that people inherit a tendency to develop diabetes, and that viruses may be involved. Type 1 is lethal unless insulin is injected to replace the missing hormone. Type 1 diabetes (formerly known as "childhood," "juvenile," or "insulin-dependent" diabetes) is not primarily a childhood problem. The adult incidence of Type 1 is similar to that for children, which is why "Type I" is now the preferred term.

Type 2 Diabetes is the most common form of diabetes, affecting approximately 90% of people with diabetes. It is characterised by insulin resistance. Insulin becomes less effective at controlling glucose levels, causing them to increase. This form of diabetes often occurs in individuals over the age of 30, however it is increasingly being identified in younger people. Type 2 diabetes has been linked to various lifestyle factors such as obesity, poor diet and lack of exercise.

The third type of Diabetes is called Gestational Diabetes. It occurs during pregnancy when the body is unable to make the amount of insulin it needs for pregnancy. Gestational diabetes usually subsides after pregnancy, however having the condition during pregnancy increases the risk of developing type 2 diabetes in the future. Approximately 60% of women who have had gestational diabetes develop type 2 diabetes, so maintaining a healthy lifestyle is important to help reduce this risk.

Pre-diabetes or "insulin resistance" is a condition that occurs when a persons fasting glucose levels are above normal, but not high enough to be diagnosed with diabetes. If proper treatment is received and implemented, this condition can be reversed before diabetes develops.

Type 1 and Type 2 Diabetes are very different conditions. While they both effect the body’s production or use of insulin, the cause and treatment for them are separate.