Superior mesenteric artery (SMA) syndrome is an uncommon disease resulting compression of the third portion of the duodenum from the superior mesenteric artery. This disease shares many common manifestations with diabetic gastroparesis, including postprandial fullness, nausea, vomiting, and bloating. Therefore, it is often overlooked in diabetic patients. Here, we report a 41-year-old man with poorly controlled diabetic mellitus who developed SMA syndrome due to rapid weight loss. The diagnosis was confirmed by computed tomography and an upper gastrointestinal series. His condition improved after parenteral nutrient, strict sugar control, and gradual weight gain.