Objective: To investigate the relationship between platelet-lymphocyte ratio (PLR) and carotid atherosclerosis (CAS) in middle-aged and elderly patients with T2DM. Methods: A total of 420 middle-aged and elderly patients with T2DM who were hospitalized in the Endocrinology Department of our hospital from September 2018 to September 2020 and were examined by ultrasound were selected as the subjects. The carotid artery intima-media thickness (CIMT) was examined by color Doppler ultrasonography, including normal CIMT group (n=111), CIMT thickening group (n=103) and CAS plaque group (n=206). The differences of serum PLR levels among the three groups were compared. Multivariate Logistic regression was used to analyze the relationship between PLR and CAS plaque formation. The receiver operating curve (ROC) was used to evaluate the value of multivariate Logistic regression model (Logit P) in the diagnosis of CAS lesions. Results: The mean value of PLR in CAS plaque group (127.86±48.54) was significantly higher than that in CIMT normal group (109.15±48.35). Multivariate Logistic regression analysis showed that after adjusting for other confounding factors, the increase of PLR was an independent risk factor for the occurrence of CAS plaque. ROC showed that the efficacy of multivariate Logit P model in the diagnosis of CAS plaque was (AUC=0.807,95％CI=0.759-0.858). Conclusions: PLR is one of the important risk factors for the occurrence of CAS lesions. At the same time, the multivariate Logistic regression model established in this study has clinical reference value in predicting CAS lesions in middle-aged and elderly patients with T2DM.