This is not a complete list, but other types of diabetes are sub-types and much less common.  Diabetes is diagnosed when fasting blood glucose rises above 6mmol/l (108mg/dl), is still above 7.8 (140mg/dl) two hours after eating, and HbA1C (glycated haemoglobin – the ‘long-term’ blood sugar marker) over 7%. 

Type 1 diabetes is classed as an autoimmune disease. In this condition, the body’s immune system attacks and destroys those cells of the pancreas that are responsible for the secretion of insulin, a hormone needed to regulate blood glucose. This means that, in people with type 1 diabetes, no or not enough glucose can reach the cells. Until the discovery of insulin and the development of synthetic insulin for injection, a diagnosis of type 1 diabetes meant certain death. 

Type 2 diabetes used to be called “adult onset diabetes” as – unlike T1D – it was only observed in older people. It was also fairly rare. Like T1D, glucose from the blood stream cannot enter the body's cells. However, in the case of T2D, the underlying cause is insulin resistance, i.e. the pancreas does produce insulin – at least in the earlier stages – but the cells are unable to recognise and utilise it. The result is, again, an inability of the cells to receive glucose.