RESUMO
Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) are serious complications associated with diabetes mellitus (DM). HHS is a common diagnosis in adults but rare in children. DKA is a usual presentation for new-onset type 1 DM, although HHS is rarely a manifestation of new-onset type 1 DM. Diagnosis and management of HHS are challenging in pediatric patients, especially if they present with a mixed picture of HHS and DKA. We report an adolescent female with a new onset of type 1 DM presented as mixed DKA and HHS. Treatment included meticulous management of fluids and continuous insulin drip with the resolution of acidosis within 24 hours and hyperosmolar state at 96 hours of admission. Early differentiation of these two entities and meticulous fluid management improves the outcome and decreases the risk of complications such as cerebral edema, renal failure, and thrombosis, among others.