Objective To investigate the association between dietary total antioxidant capacity(DTAC)and diabetes mellitus.Methods A case-control study was conducted to select 124 diabetes patients hospitalized in the En-docrinology Department of Lai'an County People's Hospital from 2021 to 2023 and 128 adults participating in physical examination at the same time as the research objects,A semi-quantitative frequency survey was used to collect the types and quantities of all foods consumed by the subjects,and the total dietary antioxidant capacity was assessed by plasma i-ron-reducing capacity(FRAP),free radical trapping antioxidant parameter(TRAP)and Trolox equivalent antioxidant capacity(TEAC)with reference to a publicly available database.According to the quartile method,the values of the a-bove two indicators were divided into four groups(Q1-Q4)from low to high.Logistic regression model was used to ana-lyze the correlation between DTAC and diabetes and prediabetes.Results Compared to the healthy control group,the intake of energy and fat in the diabetic group was higher,and the intake of vitamin C and folate was lower(P<0.05).Logistic regression analysis showed that the risk of diabetes in the group with high dietary TEAC was lower by Q3[OR(95%CI):0.10(0.02-0.46)]and Q4[OR(95%CI):0.14(0.02-0.80)]than that in the group with low dietary TEAC.After adjusting the model,the risk of developing diabetes was reduced in the group with high levels of dietary TE-AC(P<0.05)and the group with high levels of TRAP compared with the group with low levels.Conclusions Higher DTAC is inversely related to diabetes.