Diabetes mellitus is a chronic disease caused by too much sugar (glucose) in the blood. High levels of glucose in the blood can cause damage to the nerves and blood vessels if left untreated. Insulin is an important hormone secreted by beta cells in the pancreas. It regulates blood glucose levels but when things go wrong, glucose can accumulate. Without treatment diabetes can lead to long-term health problems including kidney failure, gangrene, sensory loss, ulceration, blindness and CVD.