Objective To investigate serum levels of food intake inhibitory factor-1(Nesfatin-1)and Klotho and their predictive value for secondary mild cognitive impairment(MCI)in elderly patients with type 2 diabetes mellitus(T2DM).Methods A total of 118 elderly patients with T2DM diagnosed and treated in the hospital from April 2023 to March 2024 were selected as the T2DM group,and they were divided into the non-MCI group(n=71)and the MCI group(n=47)according to the Montreal Cognitive Assessment(Mo-CA)scale.In addition,110 healthy people in the same hospital during the same period were selected as the control group.The clinical data of the patients were collected.Serum Nesfatin-1 and Klotho levels were detec-ted by enzyme-linked immunosorbent assay.Spearman and Pearson correlation analysis were used to analyze the correlation of serum Nesfatin-1 and Klotho levels with MoCA score and related clinical indicators in elder-ly patients with T2DM.Multivariate Logistic regression analysis was used to analyze the influencing factors for secondary MCI in elderly patients with T2DM.Receiver operating characteristic(ROC)curve was used to evaluate the predictive value of serum Nesfatin-1 and Klotho levels for secondary MCI in elderly patients with T2DM.Results Compared with control group,the serum levels of Nesfatin-1 and Klotho were significantly decreased in T2DM group(P<0.05).The serum levels of Nesfatin-1 and Klotho in MCI group were signifi-cantly lower than those in non-MCI group(P<0.05).Compared with the non-MCI group,the levels of fast-ing plasma glucose(FPG),insulin resistance index(HOMA-IR),reactive oxygen species(ROS)and C-reac-tive protein(CRP)were significantly increased in the MCI group(all P<0.05),and were negatively correla-ted with serum Nesfatin-1 and Klotho levels(all P<0.05).The serum levels of Nesfatin-1 and Klotho were positively correlated with MoCA score(P<0.05).Increased levels of FPG and ROS and decreased levels of Nesfatin-1 and Klotho were risk factors for secondary MCI in T2DM patients(P<0.05).The area under the curve of serum Nesfatin-1,Klotho and their combination for predicting secondary MCI in T2DM patients was 0.803,0.829 and 0.932,respectively.The combined prediction of serum nesfatin-1 and Klotho was better than each index alone(Zcombined-Nesfatin-1=3.421,P=0.001,Zcombined-Klotho=2.980,P=0.003).Conclusion The serum lev-els of Nesfatin-1 and Klotho are decreased in T2DM patients,which are significantly correlated with secondary MCI in T2DM patients,and both of them have high predictive value for secondary MCI in T2DM patients.