Severe diabetic ketoacidosis (DKA), rarely, may be associated with elevated troponin and proBNP levels in adults with a history of diabetes. However, few cases have reported this association in children with severe and complicated DKA. We describe a case of severe DKA (pH: 6.89, HCO3: 6.5) in a 14-yr-old female adolescent in which the symptoms of DKA were presented days before the diagnosis. The patient was under the effect of acidosis (Kussmaul respiration) for 12 h before admission to our hospital, where she was admitted in a critical clinical condition. After successful treatment with DKA with intensive intravenous fluid and regular insulin, the patient presented with abnormal cardiac rhythm, disturbance of interventricular septum motility, a mild decrease in left ventricular systolic function, negative T waves in leads III and aVF, and a marked increase in troponin and brain natriuretic peptide (NT-proBNP) levels. All abnormal findings completely resolved within 8 days after the initiation of DKA treatment. The phenomenon in our case was transient, and the patient had a good long-term outcome. However, it represents a challenge for clinicians; therefore, emphasis should be given to cardiac monitoring during the course of severe and prolonged DKA in children and adolescents.