Objective To investigate the correlation between thyroid function,neutrophil/lymphocyte ratio(NLR),platelet/lymphocyte ratio(PLR)and diabetic ketoacidosis(DKA).Methods A total of 272 diabetic patients admitted to the Department of Endocrinology,Anhui No.2 Provincial People's Hospital were enrolled in this study from January 2021 to March 2024 and divided into DKA group(n=74),diabetic ketosis group(DK group,n=100)and simple DM group(n=98)according to their disease conditions.Serum free triiodothyronine(FT3),free tetraiodothyronine(FT4),thyroid stimulating hormone(TSH),FPG,HbA1c,anion gap(AG),white blood cells(WBC),neutrophils(N),platelets(PLT)and lymphocytes(L)were detected in each group,and NLR and PLR were calculated.The influence factors of DKA were analyzed by logistic regression,and the diagnostic value of FT3,NLR and PLR in DKA was evaluated by receiver operating characteristic(ROC)curve.Results Hospitalization days,FPG,HbA1c,incidence of LT3S,AG,WBC,N,PLT,NLR,PLR were higher in DKA group than in DM and DK groups(P<0.05),Age,FT3,FT4,TSH,L were lower in DKA group than in DM and DK groups(P<0.05).Logistic regression analysis showed that FT3,AG,NLR and PLR were the influencing factors for DKA.ROC curve showed that the area under the curve of FT3,NLR,PLR and combined detection to predict DKA were 0.961,0.938,0.810 and 0.980,the sensitivity was 87.8%,90.5%,75.7%and 98.6%,the specificity was 95.5%,92.9%,76.3%,92.4%,and the combined detection was superior to the single detection.Conclusions FT3,NLR,PLR have a certain diagnostic value for DKA,and the combined detection of the three has a high diagnostic value,which can provide a reference for clinical diagnosis of DKA.