Abstract
OBJECTIVE: To examine the association between muscular strength and incident type 2 diabetes, independent of cardiorespiratory fitness (CRF). PATIENTS AND METHODS: A total of 4681 adults aged 20 to 100 years who had no type 2 diabetes at baseline were included in the current prospective cohort study. Participants underwent muscular strength tests and maximal treadmill exercise tests between January 1, 1981, and December 31, 2006. Muscular strength was measured by leg and bench press and categorized as age group- and sex-specific thirds (lower, middle, and upper) of the combined strength score. Type 2 diabetes was defined on the basis of fasting plasma glucose levels, insulin therapy, or physician diagnoses. RESULTS: During a mean follow-up of 8.3 years, 229 of the 4681 patients (4.9%) had development of type 2 diabetes. Participants with the middle level of muscular strength had a 32% lower risk of development of type 2 diabetes (hazard ratio, 0.68; 95% confidence interval, 0.49-0.94; P=.02) compared with those with the lower level of muscular strength after adjusting for potential confounders, including estimated CRF. However, no significant association between the upper level of muscular strength and incident type 2 diabetes was observed. CONCLUSION: A moderate level of muscular strength is associated with a lower risk of type 2 diabetes, independent of estimated CRF. More studies on the dose-response relationship between muscular strength and type 2 diabetes are needed.