Diabetic ketoacidosis DK" is a leading cause of morbidity and mortality in patients with type diabetes T DM . Individuals familiar with this complication of diabetes should be able to identify the earliest signs and symptoms and act promptly to prevent further deterioration. However, even in patients with established diabetes, the rates of DK" are considerable. This chapter discusses in detail the various aspects of DK" in the pediatric population with T DM. The prevalence and regional effects on the prevalence of DK" as well as the specific risk factors, whether disease, patient, or physician related, are reviewed. Patients with DK" experience a condition of starvation despite the abundance of metabolic substrate i.e., glucose the pathophysiological mechanisms responsible for the development of DK" are outlined. Next, a detailed discussion of the clinical aspects of DK" is provided. This includes the clinical findings at presentation, the approach to treatment, and potential complications. Prevention is the best method for reducing rates of DK". Somewhat different factors apply in patients with new-onset diabetes when compared with those with established diabetes and these are reviewed.