<p>The estimated glucose disposal rate (eGDR) serves as a novel indicator of insulin resistance, which has been shown to correlate with cardiovascular disease risk; however, its relationship with cognitive function remains unclear.This article describes a cross-sectional study design based on data from the 2011–2014 National Health and Nutrition Examination Survey (NHANES). The Weighted logistic regression and the restricted cubic spline were employed to examine the relationship between eGDR and cognitive ability.The subjects were divided into two categories: the normal group and the cognitive function decline (CFD) group, based on their cognitive scores. There were significant differences in eGDR levels between the two groups(<i>P</i> = 0.001).After adjusting for relevant covariates, notable differences were found between eGDR and cognitive function when eGDR was expressed in both continuous and categorical data forms (<i>P</i> &lt; 0.05). The stability of these findings was further confirmed through sensitivity analyses.This difference persisted in subgroups, including women, individuals with education beyond high school, moderate drinkers, and those who had not been diagnosed with stroke (<i>P</i> &lt; 0.05). A restricted cubic spline revealed a non-linear relationship with an inflection point between the two (P-for-non-linear &lt; 0.05, P-overall &lt; 0.001). This study contributes to the understanding of the relationship between eGDR and cognitive performance by identifying a potential non-linear association.</p>