Emphysematous gastritis is a rare disorder characterized by emphysematous change of the gastric wall due to infection with a gas-forming organism. Acute necrotizing esophagitis is a rare disorder with an unknown pathogenesis. Above two disorders rarely occur together, only three global cases have been reported to date. Such a case has never been reported in Korea, we report a novel case of severe emphysematous gastritis with concomitant portal venous air and acute necrotizing esophagitis in type 1 diabetes presenting with diabetic ketoacidosis. A 24-year-old man known to have type 1 diabetes and pulmonary tuberculosis was brought to the emergency room for epigastric pain with vomiting. His body mass index was 14.7, and the laboratory findings demonstrated leukocytosis and acidosis, as well as elevated serum glucose, ketone, and C-reactive protein levels. Enhanced computed tomography showed portal vein gas and edematous wall thickening without enhancement in the stomach wall, with air density along the stomach and esophageal wall. The patient required surgical intervention of total gastrectomy and cervical esophagostomy followed by esophagocolostomy and esophageal reconstruction. Early radiologic diagnosis and clinical suspicion of this disease and prompt intervention including antibiotics, decompression, and surgery are important for a good prognosis.