Serum copper modulates cognitive function in diabetic patients via an HDL-C-mediated pathway: identification of a 25 µg/dL exploratory threshold

This study identifies a diabetes-specific statistical association between serum copper, HDL, and cognitive function in DACD. The 25 µg/dL copper threshold (exploratory inflection point) marks where HDL-C-mediated effects become prominent, while sex- and age-specific threshold differences highlight population heterogeneity. This threshold offers a reference for trace element-lipid interaction research but requires validation in independent cohorts before potential use in DACD risk stratification.