The rate of obesity in Japan, defined as having a body mass index (BMI) of 25 kg/m(2) or greater, is reportedly at 24 %, a lower level of severe obesity than in the EU and US. However, the incidence of obesity-related health problems is reportedly higher among Asians. Laparoscopic sleeve gastrectomy (LSG) is the most frequently performed bariatric surgery in Japan and accounted for 54 % of such surgeries in 2011; procedures such as laparoscopic adjustable gastric banding and laparoscopic Roux-en-Y gastric bypass (LRYGB), practiced frequently worldwide, were uncommon. Possible reasons include concern over delayed postoperative discovery of gastric cancer in LRYGB, and rapid adoption of the comparatively simple LSG procedure. In type 2 diabetes mellitus (T2DM) patients, where continued pursuit of medical treatment is difficult and a potential exists for future deterioration of diabetes-complicated diseases, the criterion for surgical indication in the EU and US is a BMI of 30-35 kg/m(2), with priority given to BMI >35 kg/m(2). For Asian patients, the recommendation is to lower this indication criterion by 2.5 kg/m(2). Efficacy of metabolic surgery is anticipated particularly among T2DM patients with obesity complication, a short history of insulin treatment, and intact insulin secreting ability, and in these cases bariatric surgery should be contemplated.