Over 22 kg/m2of BMI at Young Age Is a Risk Factor for Future Diabetes in Japanese Men

Type 2 diabetes (T2DM) is easily developed in Asian adults with normal body mass index (BMI), compared with other ethnicities with similar BMI. For example, it has been shown that slightly increased BMI level (>23 kg/m2) in middle age (around 50 years old) is a risk for development of T2DM in Asians. However, it is still unclear whether slightly elevated BMI at young age within normal BMI range (<25 kg/m2) also increases the risk of T2DM later in life. To clarify this, we investigate the impacts of BMI at young age on development of T2DM later in life by historical cohort study. The study subjects are male alumni who were graduated physical education school in Japan from 1971 to 1991. From 2007 to 2017, a self-administered follow-up questionnaire was sent by mail to the subjects to ask their previous medical diagnosis of diabetes. This study analyzed 657 male alumni and covered 32-year follow-up period (interquartile range: IQR: 27-36) which included 20,607 person-years of observation. Subjects were 22 (22-22) years old at graduated college and 54 (50-59) years old at final follow-up investigation. Median BMI was 22.0 (21.1-23.0) kg/m2 at college age and 23.9 (22.3-25.6) kg/m2 at first follow-up investigation. During the period, 57 men developed diabetes. Then, the participants were categorized into four categories: BMI at college age of <21.0 kg/m2 (n=155), 21.0-22.0kg/m2 (n=172), 22.0-23.0kg/m2 (n=170), and ≥23.0kg/m2 (n=160), and the incidence of diabetes was compared. The prevalence rates of diabetes for lowest to highest BMI categories were 4.5%, 7.6%, 11.2%, and 11.3%, respectively (p=0.10), and their hazard ratios were 1.00 (reference), 1.65 (95% CI: 0.66-4.14), 2.45 (1.02-5.87), and 2.51 (1.05-6.03), respectively (p=0.02 for trend). This trend was similar after adjustment for age, year of graduation, smoking and participation in college sports club. These data suggested that over 22.0kg/m2 of BMI at young age might be a risk factor for future T2DM in Japanese men. Disclosure Y. Someya: None. Y. Tamura: None. Y. Kohmura: None. K. Aoki: None. K. Suzuki: None. S. Kawai: None. H. Daida: None.