Introduction:Type 1 diabetes mellitus (T1DM) is the most common metabolic disorder occurring in childhood with significant morbimortality. Uncontrolled diabetic patients are exposed to fatal hyperglycemic emergencies such as Diabetic ketoacidosis (DKA) characterized by hyperglycemia, acidosis, and ketosis. Although infections remain the predominant precipitating factors for (DKA), its association with mediastinitis is, to date, a rare situation. The objective of this study was to bring the importance of diagnosing the underlying etiological precipitants during DKA to enhance the management of this complication and reduce its mortality. Case Description:The authors report during this article the case of a 7-year-old male patient, known type 1 diabetic on insulin therapy for 3 years, admitted to the pediatric intensive care unit in AbderrahimHarrouchi hospital in Casablanca for severe diabetic ketoacidosis with febrile reparatory distress and whom the non-improvement of the symptomatology leads us to diagnose an acute mediastinitis complicating its fungal bronchopneumonia. Discussion:This report will review the precipitant factors, relayed by literature, associated with acute metabolic decompensation of diabetes in pediatric patients and the incidence of fungal lung infection in the diabetic population.The authors also highlight the lack of scientific data concerning the mediastinitis complicating pulmonary infections, especially in the pediatric population. Conclusion:Acute mediastinitis is a serious medical condition, commonly misdiagnosed due to the polymorphic and unspecific clinical presentation that can be related to the bronchopneumonia itself. This fatal complication being an etiological factor of a DKA considerably increases its mortality.