Diabetes, type 1: An autoimmune disease that occurs when T cells attack and destroy most of the beta cells in the pancreas that are needed to produce insulin, so that the pancreas makes too little insulin (or no insulin). Without the capacity to make adequate amounts of insulin, the body is not able to metabolize blood glucose (sugar), to use it efficiently for energy, and toxic acids (called ketoacids) build up in the body. There is a genetic predisposition to type 1 diabetes.
The disease tends to occur in childhood, adolescence or early adulthood (before age 30) but it may have its clinical onset at any age. The symptoms and signs of type 1 diabetes characteristically appear abruptly, although the damage to the beta cells may begin much earlier and progress slowly and silently.
The symptoms and signs include a great thirst, hunger, a need to urinate often, and loss of weight. Among the risks of the disease are serious complications, among them blindness, kidney failure, extensive nerve damage, and accelerated atherosclerosis. The long-term aim with treatment is to avoid these complications or, at the least, to slow their progression. There is no known cure.