Association between serum insulin level and low muscle mass in older individuals: evidence from the China Health and Nutrition Survey.

Abstract

Background: The link between serum insulin level and low muscle mass among older adults is not yet fully understood. This study seeks to investigate this association using data from a nationally representative large-scale survey.

Methods: The study utilized data from two waves of the China Health and Nutrition Survey (CHNS) conducted in 2009 and 2015. Subjects meeting the inclusion criteria were classified according to the Asia Working Group for Sarcopenia 2019 criteria. The study employed ordinary least squares (OLS) regression models to analyze the cross-sectional association between appendicular skeletal muscle mass (ASM) and serum insulin level. Additionally, based on the median insulin level in the population without low muscle mass in 2009, these individuals were divided into high insulin and low insulin groups. Logistic regression models were utilized to examine the longitudinal association between low muscle mass and serum insulin level.

Results: In 2009, a cross-sectional association study enrolled a total of 2329 participants aged over 60 years, with 53.1% women and a median age of 68.00 years. The prevalence of low muscle mass in the study population was 30.83%, with females accounting for 60.03%. In the adjusted OLS regression model based on blood biomarker, serum insulin level was positively associated with ASM (β = 0.075, 95% confidence interval (95% CI): 0.034-0.117, P < 0.01). A total of 944 individuals from the 2009 population without low muscle mass were divided into high insulin and low insulin groups based on the median insulin level, and were followed up until 2015. It was found that there was a significant difference in the incidence of low muscle mass between the two groups. (12.44% vs. 7.45%, P = 0.01). The adjusted logistic regression models indicated that higher serum insulin levels were associated with a reduced incidence of low muscle mass (Hazard ratio = 0.958, 95% CI: 0.925-0.989, P = 0.01).

Conclusions: Adequate serum insulin level could potentially serve as a protective factor in preserving healthy muscle mass among Chinese adults aged 60 and above.

Clinical trial number: Not applicable.