Diabetic ketoaciosis (DKA) is a life-threatening complication in patients with untreated diabetes mellitus (chronic high blood sugar or hyperglycemia). Near complete deficiency of insulin and elevated levels of certain stress hormones combine to cause DKA. DKA is more common among Type I diabetics, but may also occur in Type II diabetics generally when physiologically stressed, such as during an infection. Patients with new, undiagnosed Type I diabetes frequently present to hospitals with DKA. DKA can also occur in a known diabetic who fails to take prescribed insulin. DKA was a major cause of death in Type I diabetics before insulin injections were available; untreated DKA has a high mortality rate.