The protective effect of good physical fitness when young on the risk of impaired glucose tolerance when old

Background. The role of physical activity or fitness on preventing impaired glucose tolerance (IGT) has not been widely investigated. The present case control study examined the relationship between the occurrence of IGT in men in their 50s and the level of their physical fitness while in their 30s. Methods. The subjects consisted of 38 male Japan Self-Defense Forces officials in their 50s who had IGT, as diagnosed by the 75-g oral glucose tolerance test, and 60 control individuals. Nine diabetics were included in the IGT cases. As an indicator of physical fitness between the ages of 30 and 39 years, we selected the best time recorded for each individual during that decade of life for the 1,500-m physical fitness test run. We calculated the odds ratio for IGT in relation to selected risk factors (including physical fitness), and a logistic regression analysis was used to adjust for possible confounding variables. Results. The odds ratio (95% confidence interval, P value) for IGT with physical fitness in their 30s was 0.25 (0.11-0.58, P < 0.05). With adjustment for a parental history of diabetes and body mass index in both their 30s and their 50s, the odds ratio was 0.31 (0.11-0.86, P < 0.05). Conclusions. We concluded that the occurrence of IGT, including diabetes, in men in their 50s can be reduced by maintaining a high level of physical fitness while in their 30s. (C) 1999 American Health Foundation and Academic Press.