We observed two patients with diabetes who were suffering from nausea, vomiting and epigastralgia after meals. These symptoms subsided when lying on their left side. Since the 2 patients had autonomic neuropathy, at first, the symptoms seemed to be attributable to diabetic gastroparesis. However, they were diagnosed as having superior mesenteric artery syndrome by hypotonic duodenography. These finding suggest that in diabetic patients who have a history of excessive weight loss superior mesenteric artery syndrome should be ruled out even though they have autonomic neuropathy.