Type 1 diabetes is an autoimmune disease where the body's immune system destroys the insulin-producing cells in the pancreas. Without insulin, glucose builds up in the bloodstream instead of being used for energy. There is no known way to prevent type 1 diabetes, and it is usually diagnosed in children and young adults. Symptoms include increased thirst, frequent urination, weight loss, and extreme tiredness. Treatment requires lifelong insulin injections via multiple daily injections or an insulin pump.