Bariatric surgery versus medical treatment in mildly obese patients with type 2 diabetes mellitus in Japan: Propensity score‐matched analysis on real‐world data

AIMS/INTRODUCTION: To compare glycemic control 1 year after treatment in patients with mildly obese (body mass index 27.5–34.9 kg/m(2)) type 2 diabetes mellitus who underwent bariatric surgery (BS) to those who received medical treatment (MT) in Japan. MATERIALS AND METHODS: A retrospective study using real‐world data was carried out in electronic medical records from a tertiary care hospital and in the Japanese Medical Data Center Inc. claim database from 2008 to 2019. Each patient was propensity score‐matched between the BS and the MT group by age, sex, body mass index, glycated hemoglobin and type 2 diabetes mellitus duration, and compared from the index date to the 1 year post‐index. RESULTS: The study included 78 patients in the BS group and 238 patients in the MT group. The mean body mass index in the BS and the MT group was 32.1 and 32.0 kg/m(2), respectively. In the BS group, the patients underwent either laparoscopic sleeve gastrectomy with or without duodenojejunal bypass. The diabetes remission rate (glycated hemoglobin <6.5% without diabetes medication) at 1 year was 59.0% in the BS group and 0.4% in the MT group (P < 0.0001). Optimal glycemic control of glycated hemoglobin <7.0% was achieved in 75.6% in the BS group and in 29.0% in the MT group (P < 0.0001). The median monthly drug costs for metabolic syndrome decreased from $US126.5 (at baseline) to $US0.0 (at 1 year) in the BS group, whereas it increased from $US52.4 to $US58.3 in the MT group. CONCLUSIONS: BS for mildly obese patients with type 2 diabetes mellitus is more clinically‐ and cost‐effective than MT in Japan.