Laparoscopic sleeve gastrectomy with duodenojejunal bypass (LSG-DJB), which has been positioned as a novel bariatric procedure, is the combination of vertical sleeve gastrectomy and proximal intestinal bypass and is theoretically expected to have strong anti-diabetic effect. Also, preserving the pylorus, a physiological valve, leads to less occurrence of dumping syndrome and anastomotic stenosis which are often problematic after laparoscopic Roux-en-Y gastric bypass (LRYGB), a gold standard. The purpose of this study was to investigate the clinical effects of LSG-DJB on obese patients with type 2 diabetes mellitus (T2DM). Consecutive 75 obese patients (female 44/male 31) associated with T2DM who underwent LSG-DJB and were followed up for at least 1 year were analyzed. The mean age was 45.5 ± 8.6 years, and the mean preoperative body weight (BW) and body mass index (BMI) were 108.4 ± 21.4 kg and 39.6 ± 7.3 kg/m(2), respectively. The mean hemoglobin A1c (HbA1c) at the first visit was 9.0 ± 1.9 %, and the duration of T2DM from diagnosis was 7.2 ± 6.2 years. Thirty-six out of the 75 patients (48 %) were treated with insulin preoperatively. All patients were evaluated and managed under a strict multidisciplinary team approach. The follow-up rate at 1 year was 89 %. At 1 year, the mean BW and BMI significantly dropped to 74.6 ± 16.9 kg and 27.5 ± 5.7 kg/m(2), respectively. The mean percent of excess weight loss (%EWL) and percent of total body weight loss (%TWL) were 99.4 ± 42.4 and 31.6 ± 8.8 %, respectively. Consequently, 68.7 % of the patients achieved HbA1c less than 6 %, and 82.1 % of them achieved HbA1c less than 6.5 % without diabetes medications. Glycemic control of HbA1c less than 7 % was achieved in 91.0 % of the patients. The percentage of patients who satisfied the American Diabetes Association (ADA)-defined composite endpoints for cardiovascular disease (CVD) risk factor control increased from 0 % (at baseline) to 31 % (at 1 year). A meal tolerance test revealed significant reduction of glucose area under the curve (AUC) and increase of insulin AUC postoperatively. LSG-DJB for obese patients with T2DM has strong anti-diabetic effect in the short-term; however, a larger number of patients with a longer follow-up period are needed for definitive conclusions.