Neutrophil-lymphocyte ratio and systemic immune-inflammation index as predictors of cardiovascular risk and mortality in prediabetes and diabetes: a population-based study

Background The neutrophil-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) are emerging inflammatory markers related to cardiovascular outcomes. This study investigated their relationships with cardiovascular disease (CVD) and mortality among individuals with prediabetes or diabetes and assessed their predictive roles. Methods A cohort of 6871 individuals with diabetes or prediabetes from the NHANES (2001-2018) was included. Weighted multivariate logistic regression models assessed NLR and SII associations with CVD risk, while survey-weighted Cox proportional hazards models evaluated their links to mortality. The predictive accuracy of the biomarkers for mortality was quantified by receiver-operating characteristic (ROC) curve analysis. Results Individuals in the higher NLR and SII groups exhibited a high incidence of CVD. A total of 1146 deaths occurred throughout an average follow-up duration of 191 months, of which 382 were caused by CVD. Participants with higher NLR markedly increased the risk of all-cause (HR = 1.82) and cardiovascular mortality (HR = 2.07). A similar result was observed in the higher SII group. RCS analysis identified a linear correlation between NLR and CVD risk and mortality (p > 0.05), while SII showed a nonlinear correlation (p < 0.05). ROC results demonstrated that NLR exhibited a higher predictive ability in mortality than SII. Conclusions Elevated levels of NLR and SII correlated with an increased risk of CVD and both all-cause and cardiovascular mortality in individuals with diabetes or prediabetes. The NLR appears to be particularly valuable for assessing risk and predicting outcomes in these patients.