This document provides guidelines for the diagnosis and management of diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) in children and adolescents from the International Society for Pediatric and Adolescent Diabetes (ISPAD). It defines DKA biochemically and lists its clinical signs. It describes risk factors for DKA and provides recommendations for emergency assessment, monitoring, fluid replacement, insulin therapy, potassium replacement, and prevention. It also defines HHS biochemically and provides goals and recommendations for its initial fluid and insulin therapy.