Associations of AIP and ePWV with severity and risk of diabetic kidney disease in type 2 diabetes patients aged ≥ 50 years

Background Diabetic kidney disease (DKD) is a major complication of type 2 diabetes mellitus (T2DM), particularly in patients aged ≥50 years. The atherosclerotic index of plasma (AIP) and estimated pulse wave velocity (ePWV) are potential markers of atherosclerosis and arterial stiffness, but their associations with DKD severity and risk remain unclear. Objective To investigate the associations of atherosclerotic index of plasma (AIP) and estimated pulse wave velocity (ePWV) with diabetic kidney disease (DKD) severity and risk category in type 2 diabetes patients (T2DM) aged ≥ 50 years. Methods A total of 1,212 T2DM patients aged ≥ 50 years were stratified by urine albumin-to-creatinine ratio (UACR) into normoalbuminuria (A1), microalbuminuria (A2), and macroalbuminuria (A3) groups. Differences in AIP and ePWV were compared, and their relationships with UACR were assessed using correlation, regression, restricted cubic spline, and subgroup analyses. Multivariable logistic regression was used to examine associations with DKD severity and risk category, adjusting for key confounders. Receiver operating characteristic (ROC) curves evaluated the discriminative ability of AIP and ePWV, individually and combined. Results AIP and ePWV increased across A1 to A3 groups and were positively correlated with UACR (all *p* < 0.05). AIP and ePWV were positively associated with the severity and risk category of DKD ( *p* < 0.05). The combination of AIP and ePWV demonstrated improved discriminative performance for DKD (area under the curve 0.68), indicating their potential utility as non-invasive adjunctive tools. Conclusions In T2DM patients aged ≥ 50 years, AIP and ePWV are independently associated with DKD severity and risk category. The combined use of these non-invasive vascular indices may assist in early risk stratification in clinical practice.