8413 Skeletal Muscle Mass, Insulin Sensitivity, And Beta-Cell Function In The Development Of Type 2 Diabetes: A 16-Year Prospective Cohort Study

Abstract Disclosure: H. Mun: None. S. Lee: None. S. Kim: None. S. Yoo: None. J. Son: None. Background: The relationship of relative muscle mass with beta-cell dysfunction and insulin resistance in the development of type 2 diabetes is unclear. We therefore aimed to evaluate longitudinal changes in glycemia, insulin sensitivity, and beta-cell function according to muscle mass. Methods: We prospectively evaluated 7090 middle-aged and older participants without diabetes at baseline every 2 years with oral glucose tolerance tests for 16 years in the Korean Genome Epidemiology Study. Weight-adjusted appendicular skeletal muscle mass was used to derive the muscle mass index (MMI). Using linear mixed-effect models, we assessed trajectories of fasting and 2-hour post-load glucose (2hPG), the composite insulin sensitivity index (ISIcomp), the 60-minute insulinogenic index (IGI60), and the disposition index (DI) according to sex-specific MMI tertiles before diagnosis with type 2 diabetes or the completion of follow-up. Results: During a median follow-up of 13.9 years, 1742 (24.5%) participants were diagnosed with type 2 diabetes. The risk of developing type 2 diabetes gradually increased as MMI decreased (multivariable-adjusted hazard ratio 1.36; 95% CI 1.29; 1.44 per SD decline in MMI). After age- and sex adjustment, significant differences were found in fasting and 2hPG trajectories between low and high MMI tertiles during follow-up (p < 0.001 for group-by-time interaction). The low MMI tertile showed significantly lower ISIcomp and DI at baseline compared to the high MMI tertile. The rate of increase in IGI60 was significantly lower in the low MMI tertile than in the high MMI tertile (0.0021 vs. 0.0191; p < 0.001) despite a progressive decline in ISIcomp during follow-up. The rate of decrease in DI was significantly greater in the low MMI tertile than in the high MMI tertile (-0.0228 vs. -0.006; p < 0.001). Conclusion: Sufficient muscle mass in middle-aged and older adults could protect against incident type 2 diabetes by preserving beta-cell function to compensate for aging-induced reductions in insulin action, independent of obesity. Presentation: 6/1/2024