LAUSR

Type 2 diabetes mellitus (T2DM) is an important national health problem because it causes cardiovascular disease and other serious complications, shortens life expectancy, and impairs quality of life [1]. The number of T2DM patients in Japan is increasing, and was estimated to be 10 million in 2016 according to the statistics of the Ministry of Health, Labour and Welfare of Japan, or a prevalence of approximately 12.7% of the population [2]. The frequency of obesity as defined by body mass index (BMI) ≥ 30 kg/m2 among patients with T2DM is increasing in Japan, especially among men [3]. The basic treatment for obesity is lifestyle modification; and if the effect is insufficient, drug therapy may be considered. On the other hand, in severely obese patients defined as BMI ≥ 35 kg/m2, it is difficult to achieve weight loss by these methods alone. Bariatric surgery has been established in recent years as a treatment modality that can be expected to achieve long-term weight control in severely obese patients. Moreover, bariatric surgery has shown to have not only excellent weight loss effects, but also independent improvements of metabolic diseases such as T2DM [4, 5]. It also reduces the incidence of total mortality and cardiovascular events [6]. For this reason, bariatric surgery has recently come to be called “bariatric/ metabolic surgery (BMS),” and its indications have been expanded to lower BMI ranges in patients with metabolic diseases [7]. A guideline issued by Japanese Society for Treatment of Obesity in 2013 indicated that patients with a BMI ≥ 32 kg/m2 who have one or more obesity-related comorbidities and are refractory to medical treatment for more than 6 months should be considered for surgery [8]. Although the number of BMS procedures in Japan has been increasing in recent years, the absolute number is still small [9], much less than in other countries of Asia–Pacific regions [10]. In other words, there is a dilemma that many patients who are eligible for BMS do not receive appropriate treatment in Japan. With this background, the authors planned and conducted a survey on the treatment of patients with severe obesity complicated by T2DM, in cooperation with the Japan Diabetes Society. The purpose of this study was to clarify the frequency of severely obese T2DM patients who are eligible for BMS in diabetes care, as well as the actual penetration of BMS among diabetologists in Japan.