INS and sarcopenia: Future research should aim to utilize more frequent biomarker data to construct more refined IR exposure trajectory models; employ methods like Mendelian randomization to probe causality; validate findings in diverse populations; explore the mediating roles of specific pathways like inflammation, sarcopenia markers, or even the gut microbiome; and ultimately conduct randomized controlled trials to evaluate the efficacy of interventions targeting insulin sensitivity improvement on delaying frailty progression.