A 59-year-old female was referred to our institute for urinary tract infection with septicemia, thrombocytopenia, and hyperglycemia. Plain abdominal X-ray and computed tomography (CT) showed emphysema at the left renal parenchyma and urinary tract along with the perirenal inflammatory changes. These findings suggested emphysematous pyelonephritis in the early phase of occurrence in a diabetic patient. Transurethral catheterization of the left ureter was immediately performed, and occluded cloudy urine was drained. Ureteral stent was left indwelt transurethrally for easy accession in case of occlusion. E. coli was cultured in drained urine. Administration of antibiotics, insulin, and anti-coagulant was performed, and drained urine became clear in several hours. General condition and laboratory findings were improved normally in a week, and CT did not reveal the emphysematous change of the left renal unit at the 11th hospital day.