Muscle strength at young age is not associated with future development of type 2 diabetes in Japanese male athletes

Muscle strengthening activity and high muscle strength were reported to protect against the development of type 2 diabetes in middle age. On the other hand, the reported prevalence of type 2 diabetes is higher in former top-level power sports athletes compared to healthy non-athlete men. High muscle strength may be a risk factor for type 2 diabetes. However, it is not clear whether high muscle strength can predict the future development of type 2 diabetes. This study examined the relationship between muscle strength at a young age and the future development of type 2 diabetes in former Japanese college athletes by a historical cohort study. Subjects were male alumni who graduated from the Physical Education School of Juntendo University. Hand-grip strength at college age (1971-1991) and type 2 diabetes history, as determined by follow-up questionnaires (2007-2009, and 2011), were collected. Relationships between hand-grip strength and new cases of type 2 diabetes were analyzed by Cox proportional hazards models and adjusted for relative risks. Data of hand-grip strength and medical history of 617 subjects were collected. The median follow-up period was 27 years, and 29 men developed type 2 diabetes. There was no relationship between incidence of type 2 diabetes and muscle strength level after adjustment for potential risk factors. The adjusted hazard ratios (HRs) and 95% confidence intervals of the low, medium, and high muscle strength categories were 1.00 (reference), 1.12 (0.46-2.70) and 0.70 (0.25-1.92), respectively. We concluded that muscle strength at a young age does not predict the future development of type 2 diabetes in Japanese male athletes.