Association between estimated glucose disposal rate and cognitive impairment in elderly patients with type 2 diabetes mellitus: a cross-sectional study

Background Insulin resistance (IR) is a fundamental pathophysiological characteristic of type 2 diabetes mellitus (T2DM) and is intricately related to neurodegeneration. This study sought to investigate the correlation between estimated glucose disposal rate (eGDR), an easily accessible and effective indicator of IR, and cognitive impairment (CI) in elderly patients with T2DM. Methods This cross-sectional study included 871 elderly patients with T2DM. The eGDR was calculated from glycated hemoglobin (HbA1c), waist circumference and hypertension status to evaluate the extent of IR in patients. Cognitive function was assessed in all participants utilizing the Montreal Cognitive Assessment (MoCA). Linear and logistic regression analyses were performed to evaluate the association between eGDR and cognitive function. Restricted cubic spline (RCS) analysis and threshold effect analysis were conducted to elucidate the nonlinear relationship between eGDR and CI. Results The eGDR levels were significantly lower in the CI group compared to the normal cognition group. Linear regression analysis indicated that eGDR was positively correlated with MoCA scores when expressed as continuous or categorical data after fully adjusting for covariates. Logistic regression analysis revealed that, after adjusting for all covariates, each unit increase in eGDR was associated with an 8% reduction in the risk of CI (OR: 0.92, 95% CI: 0.85-0.99, P < 0.05). Participants in the highest eGDR quartile exhibited a 38% lower risk of CI compared to those in the lowest eGDR quartile (OR: 0.62, 95% CI: 0.39-0.99, P < 0.05). RCS analysis and threshold effect analysis demonstrated a nonlinear relationship between eGDR and CI ( P for non-linearity=0.001). When eGDR was