Novel composite renal indicators outperform traditional markers in identifying type 2 diabetes risk in middle-aged and older Chinese adults

BACKGROUND: the rising coexistence of type 2 diabetes (T2DM) and chronic kidney disease (CKD) poses a major health challenge. Traditional renal biomarkers have limitations in characterizing renal-metabolic alterations associated with prevalent T2DM. This study evaluated composite renal indicators and their associations with prevalent T2DM in middle-aged and older Chinese adults. METHODS: we conducted a cross-sectional analysis using data from the China Health and Retirement Longitudinal Study (CHARLS, 2015 wave, n = 8,841). We compared the associations of eight renal-related indicators-including estimated glomerular filtration rate (eGFR), the difference between cystatin C- and creatinine-based eGFR (eGFR-diff), creatinine clearance rate (CCR), serum uric acid-to-creatinine ratio (SUA/Scr), and uric acid-to-high-density lipoprotein cholesterol ratio (UHR)-with prevalent T2DM using multivariable logistic regression. Discriminatory ability was assessed using receiver operating characteristic (ROC) curves. RESULTS: in the fully adjusted model, UHR demonstrated the strongest association with prevalent T2DM (OR = 1.35 per interquartile range [IQR] increase; p < 0.001), followed by CCR (OR = 1.15 per IQR; p = 0.004) and eGFR-diff (OR = 1.15 per IQR; p < 0.001). SUA/Scr showed a non-linear J-shaped relationship. UHR had the highest discriminatory ability (AUC = 0.58), showing a slightly higher AUC than eGFR-diff (0.55) and traditional eGFR (0.53). CONCLUSION: in this cross-sectional study, composite renal indicators-particularly UHR, eGFR-diff, and CCR-showed stronger associations with prevalent T2DM than traditional markers. However, the modest AUCs of all individual indicators suggest they are insufficient as standalone screening tools. These findings support further investigation into the potential role of simple renal-metabolic indices as part of a broader T2DM risk assessment framework for older Chinese adults.