Diabetic ketoacidosis (DKA), resulting from severe insulin deficiency, accounts for most hospitalization and is the most common cause of death, mostly due to cerebral edema, in pediatric diabetes. This article provides guidelines on management to restore perfusion, stop ongoing ketogenesis, correct electrolyte losses, and avoid hypokalemia and hypoglycemia and the circumstances that may contribute, in some instances, to cerebral edema (overhydration, rapid osmolar shifts, hypoxia). These guidelines emphasize the importance of monitoring glycemia, electrolytes, hydration, vital signs, and neurologic status in a setting where response can be rapid if necessary (e.g., mannitol for cerebral edema). Most important is the prevention of DKA in established patients by close supervision of those most likely to omit insulin, or during illness, and a high index of suspicion for diabetes to prevent deterioration to DKA in new patients, particularly those under age 5, who are at greatest risk of complications.