Diabetes mellitus, commonly referred to as diabetes, is a disease characterised by high blood sugar (blood glucose) levels. Normally, these levels are controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood sugar level. When the blood glucose rises (e.g. after eating), insulin is released from the pancreas to normalise the glucose level. With diabetes, the absence or insufficient production of insulin causes hyperglycaemia (raised blood glucose levels). This can result in several problems, including: blurred vision, excessive thirst, fatigue; nausea; frequent urination, weight loss despite an increase in appetite; bladder, skin and vaginal infections. There are three main types of diabetes: Type 1 diabetes is usually diagnosed early in life. With this type, little or no insulin is made, so daily injections of insulin are needed. The exact cause is unknown, but genetics, viruses and autoimmune problems may play a role. Patients with type 1 diabetes usually develop symptoms over a short period of time. Type 2 diabetes is far more common than type 1, and usually occurs in adulthood. The pancreas does not make enough insulin to keep blood glucose levels normal. This diabetes develops slowly, so some people may experience no symptoms. Gestational diabetes develops during pregnancy in a woman who does not have diabetes. Various blood tests are used to diagnose diabetes. Although diabetes is a chronic (lifelong) condition, it can be controlled. The immediate aim is to lower high blood glucose levels and treat diabetic ketoacidosis (when the body cannot use glucose as a fuel fat is used instead; by-products of fat breakdown, called ketones, build up in the body). Long-term aims are to reduce symptoms and prevent diabetes-related complications such as blindness, heart disease, kidney failure and amputation of limbs. These goals are accomplished through: blood pressure and cholesterol control; medication or insulin use; self-testing of blood glucose levels; exercise; foot care; meal planning and weight control; education and support.