Diabetic ketoacidosis is a severe complication of type I diabetes. A 13-year-old female (40 kg) patient was admitted to our Intensive Care Unit with severe metabolic acidosis (pH: 6.8), hyperglycemia (835 mg/dL) and coma. Her hemodynamic conditions were unstable and, even though a large amount of plasma expanders, crystalloids, and inotropic support were supplied, the patient went into cardiac arrest in the first hour of treatment. After resuscitation, a better hemodynamic balance was achieved and metabolic acidosis was treated with fluid replacement therapy, continuous insulin infusion, and Tris-hydroxymethyl aminomethane (THAM) as a buffering agent. This therapy rapidly improved her metabolic conditions. The patient was discharged 5 days after Intensive Care Unit admission in good condition and without neurological sequelae.