title: Body mass index and mortality among Japanese patients with type 2 diabetes: pooled analysis of the Japan diabetes complications study and the Japanese elderly diabetes intervention trial.
abstract: BACKGROUND
  Previous studies on the association between body mass index (BMI) and mortality in diabetes do not necessarily provide a comprehensive view in terms of the global population because of the exclusion of individuals with a BMI less than 18.5 kg/m(2).
  
  
  OBJECTIVE
  The objective of the study was to examine the association between BMI and mortality.
  
  
  METHODS
  We analyzed pooled data from 2 cohorts of 2620 Japanese patients with type 2 diabetes followed up for 6.3 years. Patients with a history of cardiovascular disease or cancer were excluded.
  
  
  METHODS
  The end point was all-cause mortality. Hazard ratios were estimated by Cox regression adjusted for age, smoking, leisure-time physical activity, and other confounders.
  
  
  RESULTS
  An analysis using BMI categories of 14.4-18.5 (5.2%), 18.5-22.4 (37.3%), 22.5-24.9 (31.0%), and 25.0-37.5 kg/m(2) (26.6%) revealed no significant trend in mortality among patients with a BMI of 18.5 kg/m(2) or greater (trend P = .69). In contrast, the hazard ratio of patients with a BMI less than 18.5 kg/m(2) vs 22.5-24.9 kg/m(2) was 2.58 (95% confidence interval 1.38-4.84; P < .01). Exclusion of deaths in the first 4 years of follow-up decreased the hazard ratio only slightly.
  
  
  CONCLUSIONS
  The lowest mortality rate was observed among patients with a BMI of 18.5-24.9 kg/m(2), and obesity had no benefits regarding mortality. Further research is needed in lean patients, especially among aging populations in East Asia.
authors.affiliation: Department of Pharmacoepidemiology (Sh.T., Sa.T.), Graduate School of Medicine and Public Health, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8507, Japan; Department of Biostatistics (S.I., Y.O.), School of Public Health, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; The Institute for Adult Diseases (Y.A.), Asahi Life Foundation, Tokyo 100-0005, Japan; Department of Internal Medicine (N.Y.), University of Tsukuba Institute of Clinical Medicine, Tsukuba, Ibaraki 305-8577, Japan; Tokyo Metropolitan Geriatric Hospital (A.A., H.I.), Tokyo 173-0015, Japan; and Department of Hematology, Endocrinology, and Metabolism (H.S.), Niigata University Faculty of Medicine, Chuo-ku, Niigata 951-8510, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Tanaka
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tanaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iimuro
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Akanuma
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Yamada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Araki
authors.forename: Hideki
authors.initials: H
authors.lastname: Ito
authors.forename: Hirohito
authors.initials: H
authors.lastname: Sone
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015331:Cohort Studies; D048909:Diabetes Complications / Q000401:mortality* / Q000473:pathology*; D003924:Diabetes Mellitus, Type 2 / Q000401:mortality* / Q000473:pathology*; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors