To investigate the correlation between the platelet-to-lymphocyte ratio (PLR) and the risk of cardiovascular disease mortality in elderly patients with diabetes mellitus (DM) based on samples from a public database in the United States.

Data on demographic characteristics and laboratory indicators of participants from the National Health and Nutrition Examination Survey (NHANES) database from 2009 to 2018 were collected, along with mortality data from the National Death Index as of December 31, 2019. A weighted Cox regression model, subgroup analysis, and restricted cubic spline (RCS) were used to explore and visualize the correlation between Log₂PLR values and cardiovascular disease mortality in elderly DM patients. The accuracy of Log₂PLR in predicting survival outcomes was assessed using receiver operating characteristic (ROC) analysis.

A total of 1 323 elderly DM patients were included in this study, with an average follow-up of 4.86 years. Ninety-one patients died from cardiovascular disease, resulting in a mortality rate of 6.88%. Both univariate and adjusted Cox regression model results indicated that a high Log₂PLR (≥7.08) was associated with cardiovascular disease mortality (HR1=2.71, 95%CI: 1.61-4.56; aHR3=2.75, 95%CI: 1.60-4.72). RCS analysis showed a linear positive correlation between Log₂PLR and cardiovascular mortality (P_non-linear=0.141). There were no significant interactions between age, sex, BMI,history of hypertension, ethnicity, education level, and Log₂PLR (P>0.05). The ROC curve demonstrated that the area under the curve (AUC) for Log₂PLR predicting cardiovascular disease mortality at 1, 3, 5, and 7 years were 0.68, 0.69, 0.67, and 0.63,respectively. When combined with age, the AUC for predicting cardiovascular disease mortality at these time points was greater than 0.70.

PLR is associated with a high risk of cardiovascular disease mortality in elderly DM patients and has certain predictive value regarding the risk of mortality from cardiovascular disease.