ObjectiveTo evaluate the changes of nutritional status following sleeve gastrectomy with ileal interposition duodenojejunal bypass operation in treatment of nonobese type 2 diabetes mellitus. MethodsA total of 47 patients submitted to sleeve gastrectomy with ileal interposition duodenojejunal bypass operation from March 2009 to November 2011 in this hospital were retrospectively analyzed. Serum iron, calcium, vitamin B12, folic acid, albumin (Alb), hemoglobin (Hb), glycosylated hemoglobin (HbA1c), and body mass index (BMI) were assessed before operation and on 6, 12, 24, and 36 months after operation. Results①The values of Alb, Hb, HbA1c, and iron after operation were significantly lower than those of the corresponding values before operation (P < 0.01), the values of calcium, vitamin B12, folic acid, and BMI had no significant differences between after operation and before operation (P > 0.05).②The incidences of the lower Alb and lower iron after operation were significantly higher than those before operation (P < 0.01), the other indexes had no significant differences between after operation and before operation (P > 0.05). ConclusionsSleeve gastrectomy with ileal interposition duodenojejunal bypass operation is an effective treatment of nonobese type 2 diabetes mellitus. However, nutritional deficiency is one of its side effects, which should be properly diagnosed and handled in order to improving the patient's quality of life and preventing related complications.