Abstract
BACKGROUND: The red blood cell distribution width-to-albumin ratio (RAR) is a novel hematological biomarker that integrates information on inflammation and nutritional status. While RAR has been applied in assessing risks for various chronic diseases, its association with diabetic kidney disease (DKD) remains unclear. This study aims to evaluate the relationship between RAR and the risk of DKD in diabetic patients, exploring its potential value in early risk identification. METHODS: Utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2005 to 2020, we included 7,191 eligible adult participants diagnosed with diabetes. RAR was categorized into quartiles, and weighted multivariable logistic regression along with restricted cubic spline (RCS) models were employed to assess the association between RAR levels and the prevalence of DKD. Subgroup and sensitivity analyses were conducted to validate the robustness of the findings. RESULTS: The RAR level was significantly higher in the DKD group compared to the non-DKD group (p < 0.001), and the prevalence of DKD increased progressively across RAR quartiles (25.20%, 30.17%, 39.34%, and 43.33%, p < 0.001). In the unadjusted model, each one-unit increase in RAR was associated with a 76.4% higher risk of DKD (OR = 1.764, 95% CI: 1.541-2.017, p < 0.001). Participants in the highest RAR quartile (Q4) had a 2.269-fold increased risk of DKD compared to those in the lowest quartile (Q1) (95% CI: 1.809-2.846, p < 0.001). RCS analysis suggested a potentially linear association between RAR and DKD risk, with no significant non-linear trend observed after adjusting for covariates (p > 0.05). Subgroup analysis revealed that the association remained consistent across most strata, although significant interactions were found for sex and BMI (P for interaction < 0.05), with stronger associations observed in males and in participants with higher BMI. Sensitivity analyses confirmed the robustness of these findings. CONCLUSION: Elevated RAR levels are significantly associated with increased risk of diabetic kidney disease among individuals with diabetes, suggesting its strong predictive potential. As a simple and cost-effective biomarker, RAR may serve as a useful tool for early DKD risk screening and stratification. However, prospective studies are warranted to further validate its clinical utility.