title: Trajectory of body mass index before the development of type 2 diabetes in Japanese men: Toranomon Hospital Health Management Center Study 15.
abstract: OBJECTIVE
  We aimed to investigate the long-term trajectory of general adiposity assessed by the body mass index (BMI) before the onset of type 2 diabetes in Japanese individuals.
  
  
  METHODS
  We retrospectively examined data on 1,553 Japanese men without diabetes. Mean BMI and incident cases of diabetes (diabetes indicated by fasting glucose concentrations ≥7.0 mmol/L, a self-reported history of clinician-diagnosed diabetes, or glycated hemoglobin ≥6.5% (≥48 mmol/mol) were assessed on an annual basis over a 10-year period after the baseline examination.
  
  
  RESULTS
  Mean (standard deviation) BMI at the time of diagnosis was 24.4 kg/m(2) (3.1 kg/m(2)) among cases of diabetes (n = 191). An increasingly high BMI was associated with the early stage of the disease development, such as an 8- to 10-year prediagnosis period; individuals who developed diabetes experienced a prolonged and stable elevated BMI of ≥24.4 kg/m(2) over the 8 years before the diagnosis of diabetes. The mean BMI among the non-cases of diabetes did not exceed 23.2 kg/m(2) throughout the period.
  
  
  CONCLUSIONS
  These results suggested that Japanese men who eventually developed diabetes during the 10-year observation period were not characterized as obese, but had stable high-normal BMIs before the onset of diabetes. Previous evidence showed that values for glycemic markers rapidly increased before the development of diabetes; however, the present study showed a slight gain in BMI in the earlier stage of the natural history of diabetes followed by a prolonged period of overweight.
authors.affiliation: Department of Internal Medicine, Niigata University Faculty of Medicine Niigata, Japan ; Health Management Center, Toranomon Hospital Minato-ku, Japan.
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Heianza
authors.affiliation: Health Management Center, Toranomon Hospital Minato-ku, Japan ; Okinaka Memorial Institute for Medical Research Tokyo, Japan.
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Arase
authors.affiliation: Department of Internal Medicine, Niigata University Faculty of Medicine Niigata, Japan ; Health Management Center, Toranomon Hospital Minato-ku, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kodama
authors.affiliation: Health Management Center, Toranomon Hospital Minato-ku, Japan ; Okinaka Memorial Institute for Medical Research Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuji
authors.affiliation: Department of Pharmacoepidemiology, Graduate School of Medicine and Public Health, Kyoto University Kyoto, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Internal Medicine, Niigata University Faculty of Medicine Niigata, Japan ; Health Management Center, Toranomon Hospital Minato-ku, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Saito
authors.affiliation: Health Management Center, Toranomon Hospital Minato-ku, Japan ; Okinaka Memorial Institute for Medical Research Tokyo, Japan.
authors.forename: Shigeko
authors.initials: S
authors.lastname: Hara
authors.affiliation: Department of Internal Medicine, Niigata University Faculty of Medicine Niigata, Japan ; Health Management Center, Toranomon Hospital Minato-ku, Japan.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Sone
keywords: Body mass index trajectory; Prediction; Type 2 diabetes