Objective To explore the clinical significance of epigenetic modification factors and metabolites in the early diagnosis and differential diagnosis of pancreatic cancer by detecting the levels of circulating nu-cleosomes,lactic acid and pyruvate in the serum of patients with pancreatic ductal adenocarcinoma,patients with other pancreatic tumors and healthy people.Methods A total of 26 patients with pancreatic ductal ade-nocarcinoma admitted to Peking University Third Hospital from January 2022 to April 2023 were selected as the experimental group.The other pancreatic tumor group included 8 cases of solid pseudopapillary tumor of the pancreas,11 cases of serous cystadenoma of the pancreas,and 9 cases of neuroendocrine tumor of the pan-creas.Another 26 healthy individuals who underwent outpatient examinations during the same period were se-lected as the health control group.Enzyme linked immunosorbent assay and targeted metabolomics were used to detect the expression levels of circulating nucleosomes,lactate,and pyruvate in serum,respectively.SPSS26.0 statistical software was used for multivariable statistical analysis to compare whether the difference in serum expression in the experimental group,other pancreatic tumor group and the health control group was statistically significant,and the metabonomics results of pancreatic cancer patients at different stages in the public database were analyzed by bioinformatics.Results There were statistically significant differences in the expression levels of lactate(P＜0.001),pyruvate(P＜0.001),and circulating nucleosomes(P＜0.001)be-tween the experimental group and the health control group,suggesting that the three had high sensitivity and specificity for the diagnosis of pancreatic ductal adenocarcinoma.Moreover,the expression levels of the three in the serum of the experimental group were significantly higher than those in the serum of other pancreatic tumor group,suggesting that these could be used to distinguish the types of pancreatic tumors.The serum ex-pression levels of the three in other pancreatic tumor group were significantly higher than those in the health control group,which were expected to become new risk indicators for pancreatic tumors.Among them,pyruvic acid showed the most significant difference in the combined model.Bioinformatics analysis indicated that pyru-vate and lactate were differential metabolites in patients with pancreatic cancer at different stages.Conclusion Circu-lating nucleosomes,lactic acid and pyruvate have high sensitivity and specificity among the three groups,which could be used as new markers of pancreatic cancer.