Objective To analyze the relationship between cognitive dysfunction and glomerular filtration rate(eGFR)in elderly patients with type 2 diabetic nephropathy (T2DN) through a cross-sectional study.Methods One hundred and eighty-six elderly patients with type 2 diabetes mellitus (T2DM)admitted to the Department of Endocrinology of the Second People's Hospital of Nantong City from January 2018 to December 2021 were selected for the study,and were divided into 81 cases in the control group(eGFR≥60 ml/[min·1.73 m2])and 105 cases in the T2DN group(eGFR＜60 ml/[min·1.73 m2])according to eGFR values,and the patients were collected general information (including age,gender,duration of diabetes,blood pressure,years of education,creatinine,glycated haemoglobin,triglycerides,high-density cholesterol and low-density cholesterol)was collected,together with the Montreal cognitive assessment(MoCA)scale and the repeatable battery of mental status (RBANS),to compare whether there were differences in cognitive function between the two groups.Results The course of diabetes in T2DN group was longer than that in control group,systolic blood pressure,diastolic blood pressure,glycosylated hemoglobin,creatinine and eGFR were higher than those in control group,and the incidence of mild cognitive impairment(MCI)was higher than that in control group,with statistical significances (P ＜0.05).There were no significant differences in age,sex,years of education,MoCA score,triglyceride,high density lipoprotein cholesterol and low density lipoprotein cholesterol between the two groups(P＞0.05).eGFR level in T2DN patients was positively correlated with immediate memory score,visual span score,attention score,delayed memory score and RBANS total score(P＜0.05),but not significantly correlated with speech function score(P＞0.05).After controlling for covariates with partial correlation coefficient,eGFR level in T2DN patients was the influencing factor for RBANS total score and immediate memory score,visual span score,attention score,and delayed memory score.Conclusion Patients with T2DN are at higher risk of cognitive impairment,and their eGFR levels may affect cognitive function.