Preserved Lower Limb Muscle Mass Prevents Insulin Resistance Development in Nondiabetic Older Adults
Toshiaki Seko, Hiroshi Akasaka, Masayuki Koyama, Nobuaki Himuro, Shigeyuki Saitoh, Tetsuji Miura, Mitsuru Mori, Hirofumi Ohnishi
Abstract
OBJECTIVE: To investigate roles of sarcopenia indexes in prediction of development of insulin resistance in nondiabetic older adults. DESIGN: A 2-year follow-up cohort. SETTING AND PARTICIPANTS: The Tanno-Sobetsu study, a prospective observational cohort, included 194 community-dwelling nondiabetic older adults during 2017-2019. METHODS: Lower limb, upper limb, appendicular, and trunk muscle masses by a bioelectrical impedance analysis, grip strength, knee extension torque, and walking speed were measured in study participants aged ≥65 years (79 men and 115 women) at baseline. Muscle mass and strength were divided by the weight, and then multiplied by 100 to calculate the weight ratio (%). Insulin resistance was assessed by homeostasis model (HOMA-IR) at baseline, and the study participants whose HOMA-IR was less than 1.73 at baseline were followed for a maximum of 2 years. The study endpoint was development of insulin resistance defined as HOMA-IR ≥1.73. The adjusted hazard ratio (HR) of each sarcopenia component for development of insulin resistance was calculated. RESULTS: Lower limb muscle mass (HR 0.88, 95% CI 0.79-0.98) and appendicular muscle mass (HR 0.89, 95% CI 0.81-0.99), but not other sarcopenia components, were associated with the development of insulin resistance, independently of sex and age, HOMA-IR, and waist circumference at baseline. CONCLUSIONS AND IMPLICATIONS: The loss of lower limb muscle mass is a significant risk factor for development of insulin resistance independently of obesity in nondiabetic older adults. The lower limb muscle mass may be a novel target of interventions for the prevention of diabetes in older adults.