LAUSR

Abstract Objectives Hyperglycemic hyperosmolar state (HHS) is one of the most severe acute complications of diabetes mellitus (DM) characterized by severe hyperglycemia and hyperosmolality without significant ketosis and acidosis. What is new? Since HHS in the pediatric population is rare and potentially life-threatening, every reported case is very valuable for raising awareness among healthcare professionals. Case presentation A 7-year-old boy with previously diagnosed Joubert syndrome was admitted due to vomiting, polydipsia and polyuria started several days earlier. He was severely dehydrated, and the initial blood glucose level was 115 mmol/L. Based on clinical manifestations and laboratory results, he was diagnosed with T1DM and HHS. The treatment with intravenous fluid was started and insulin administration began later. He was discharged after 10 days without any complications related to HHS. Conclusions Since HHS has a high mortality rate, early recognition, and proper management are necessary for a better outcome.