Date Published: January 24, 2019
Publisher: Public Library of Science
Author(s): Yuki Someya, Yoshifumi Tamura, Yoshimitsu Kohmura, Kazuhiro Aoki, Sachio Kawai, Hiroyuki Daida, Hisashi Naito, Claudia Kimie Suemoto.
There is a high incidence of type 2 diabetes in Asian adults, even those with a normal body mass index (BMI) (<25.0 kg/m2). For example, it has been shown that a slightly increased BMI (>23 kg/m2) at middle age is a risk factor for type 2 diabetes in Asians. In this historical cohort study, we investigated whether a slightly increased BMI at college age was also a risk factor for future diabetes in Japanese men.
Six hundred and sixty-one male alumni who graduated from a physical education school between 1971 and 1991 and who responded to follow-up investigation between 2007 and 2017 were included in this study. Participants were categorized into four categories: college BMI of <21.0 kg/m2, 21.0–22.0 kg/m2, 22.0–23.0 kg/m2, and ≥23.0 kg/m2, and the incidence and risk ratio of diabetes were compared between groups. The median follow-up period was 32 years (interquartile range, IQR: 27–36), which included 20,983 person-years of observation. Subjects were 22 (22–22) years old at college graduation, and 55 (50–59) years old at the final follow-up investigation. During the study period, 56 men developed diabetes; the prevalence rates for the lowest to highest BMI categories were 4.4%, 7.6%, 10.5%, and 11.3%, respectively, and their adjusted hazard ratios were 1.00 (reference), 1.77 (95% CI: 0.68–4.30), 2.42 (1.00–5.84), and 2.53 (1.06–6.07), respectively (p = 0.03 for trend). Our data suggest that a BMI over 22.0 kg/m2 at college age is a risk factor for diabetes later in life in Japanese men.
According to the World Health Organization (WHO), diabetes is associated with 1.6 million deaths per year and is recognized as one of the top 10 causes of death worldwide . Overweight and obesity, defined by body mass indexes (BMIs) of more than 25 and 30 kg/m2, respectively, have been reported as risk factors for not only type 2 diabetes, but also for hypertension, dyslipidemia, cardiovascular disease (CVD), and mortality [2–6]. The prevalence of type 2 diabetes is rapidly increasing in Asian countries, and patients with diabetes in Asia are characterized by a lower BMI than those in Western countries; for example, the mean BMI of Asian patients with type 2 diabetes was reported to be approximately 23 kg/m2 . Further, metabolic disorders are also more common in Asians than in BMI-matched Caucasians [8, 9]. In fact, a slightly increased BMI (>23 kg/m2) in middle age (around 50 years old) is recognized as a risk factor for the development of type 2 diabetes in Koreans and Japanese [10, 11]. Accordingly, the American Diabetes Association recommends a BMI cutoff value of 23.0 kg/m2 for screening of type 2 diabetes in Asian Americans .
In this study, we investigated the relationship between BMI at college age and the future development of diabetes in Japanese male alumni of a physical education school. Hazard ratios for diabetes in the BMI categories of 22–23 kg/m2 and over 23 kg/m2, adjusted for potential confounding factors, were 2.4 and 2.5 times higher, respectively, than that for the BMI category of under 21.0 kg/m2. These data suggest that a slightly increased BMI at college age, even when within the normal range, may be associated with the future development of diabetes in Japanese men.
In conclusion, our data suggest that a BMI over 22.0 kg/m2 at college age is a significant risk factor for future diabetes in Japanese men.