Thrombotic thrombocytopenic purpura (TTP) secondary to diabetic ketoacidosis has been rarely reported and is considered as a rare complication. If left untreated, this condition could be life threatening with considerable morbidity and mortality. Herein, we report a 6-year-old girl with reduced consciousness and respiratory distress with a history of polydipsia and polyuria in the 2 weeks before hospitalization. The patient was initially diagnosed as diabetic ketoacidosis based on clinical and laboratory findings and treated accordingly. After treatment and during hospitalization although she had gained relative consciousness, she experienced seizure and reduced consciousness again. Considering laboratory and clinical findings and the patient's underlying conditions (thrombocytopenia, renal failure, and high lactate dehydrogenase), TTP was suspected although ADAMTS13 test could not be done. Treatment with plasmapheresis was initiated, and after 48 h, the patient was conscious, and laboratory indices became normal within a few days. The patient was discharged after full recovery. TTP should be considered as a rare complication of diabetic ketoacidosis in patients with thrombocytopenia, renal failure, and reduced consciousness and should be immediately treated.