Associations of metabolic syndrome and its components with sarcopenia, and the mediating role of insulin resistance: Findings from NHANES database.

Background: To investigate the association between metabolic syndrome (MetS) and its components with sarcopenia, and to explore the extent to which insulin resistance (IR) mediates this association, using data from the National Health and Nutrition Examination Survey (NHANES).

Methods: We analyzed cross-sectional data from 15,779 adults in the NHANES from 1999 to 2006 and 2011-2018. Multivariable logistic regression models were used to determine the odds ratios (ORs) between MetS, its components, the number of MetS components, and sarcopenia. Mediation analysis was performed to explore the role of the homeostatic model assessment of insulin resistance (HOMA-IR) in MetS and its components-induced sarcopenia.

Result: In the fully adjusted model, MetS increased the prevalence of sarcopenia by 1.96-fold (95% CI: 1.73-2.22). Among the individual components, central obesity, hypertension, and hyperglycemia were associated with an increased prevalence of sarcopenia. Sarcopenia prevalence also increased linearly with the number of MetS components, with the highest prevalence observed in the presence of all five components (OR: 3.80, 95% CI: 2.79-5.16). Sex-stratified analysis showed that the prevalence of MetS for sarcopenia was higher in males than females. The mediating effects of HOMA-IR on the association between MetS and its components (central obesity, hypertension, and hyperglycemia) with sarcopenia were significant, with mediation effects of 51.7%, 30.7%, 33.2%, and 79.1%, respectively. There was no significant direct association between hyperglycemia and sarcopenia beyond the HOMA-IR pathway.

Conclusion: MetS and its individual components, excluding hypertriglyceridemia and low high density lipoprotein cholesterol, were associated with a higher prevalence of sarcopenia, especially in males. This association was partially or fully mediated by IR.