Obesity and the risk of diabetes mellitus in middle-aged Japanese men.

The morbidity of diabetes mellitus is increasing gradually in Japanese populations. It is important to clarify the risk factors of diabetes in Japanese populations in order to take adequate measures against the increasing morbidity of diabetes. In order to evaluate the link between past and concurrent obesity and diabetes in middle-aged Japanese men, we conducted a worksite-based historical cohort study in Okayama, Japan in 1999. Annual health examination data of middle-aged male workers in a worksite were collected. The relative risks of past and concurrent obesity for developing diabetes were calculated. Subjects with a past history of obesity at between 40 and 50 years of age had a significantly higher risk of developing diabetes by age 55 than did subjects in the normal weight group. These results suggest that, in order to prevent diabetes in middle-aged Japanese men, health guidance for normal weight maintenance should be provided not only for middle-aged men, but also for men under age 40.