Aim To investigate the effect of serum Nε-carboxymethy lysine (CML) on different degrees of carotid calcification in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). MethodsFrom January 2016 to June 7,6 patients were selected from the Affiliated Hospital of Jiangsu University, including 148 T1DM patients, 191 T2DM patients and 167 patients without diabetes. Color Doppler ultrasound was used to detect bilateral carotid arteries in all patients. The severity of carotid calcification was evaluated according to 0-8 points. The patients were divided into low calcification group (scores:1-4) and high calcification group (scores:5-8). The general clinical data, physical examination results and laboratory examination results were recorded, and the serum CML level was measured by enzyme-linked immunosorbent assay. Multivariate Logistic regression analysis was conducted to determine independent predictors of carotid calcification in T1DM and T2DM patients. During follow-up, CML was retested and major adverse cardiac and cerebrovascular event (MACCE) were followed up. Results In the high calcification group and low calcification group, the CML, carotid intima-media thickness and low density lipoprotein cholesterol level of diabetic patients were higher than those of non-diabetic patients (P＜0.05), and the levels of T2DM patients were higher than levels of T1DM patients (P＜0.05). Multivariate Logistic regression analysis showed that CML was an independent predictor of carotid calcification degree in T1DM patients (OR 2.5,5%CI 1.368-2.996, P＜0.05), and also an independent predictor of carotid calcification degree in T2DM patients (OR 2.5,5%CI 1.481-4.171, P＜0.05). The significant increase of CML during follow-up was correlated with MACCE. Conclusion CML is an independent predictor of different degrees of carotid calcification in T1DM and T2DM patients, and to some extent, it can predict the occurrence of diabetic cardiovascular and cerebrovascular events.