Objective To explore the influencing factors associated with cognitive dysfunction in the elderly with type 2 diabetes mellitus (T2DM). Methods A total of 204 hospitalized T2DM old patients (≥60 years old) admitted in our department from June 2017 to May 2018 were enrolled in the study. According to the result of Montreal Cognitive Assessment (MoCA) test, they were divided into the cognitive dysfunction group (n=98) and normal cognitive function group (n=106). The indicators of physical examination and laboratory tests were collected. The estimated glomerular filtration rate (eGFR) was calculated by using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. SPSS statistics 19.0 was used for data analysis, and Chi-square test, Student′s t test or Mann-Whitney U test was employed for comparison between the groups. Multivariate logistic regression analysis was used to assess the risk factors for cognitive dysfunction. Results The cognitive dysfunction group was older in age [(68.4±7.7) vs (66.0±6.7)years], and had significantly higher proportions of the patients with osteoporosis [35.71%(35/98) vs19.81%(21/106)] and eGFR <60ml/(min·1.73m²) [26.53%(26/98) vs 12.26%(13/106)], but lower MoCA score [(20.36±4.07) vs (27.02±1.49)] and shorter educational duration [(8.85±4.14) vs (12.35±3.30)years] when compared with the normal cognitive function group (all P<0.05). Multivariate logistic regression analysis showed that age (OR=1.05,5%CI 1.01-1.10; P=0.011) and eGFR <60ml/(min·1.73m²) (OR=2.15,5%CI 1.08-4.26; P=0.029) were independent risk factors for cognitive dysfunction. Conclusions Age and eGFR <60ml/(min·1.73m²) are risk factors for cognitive dysfunction in the elderly with T2DM. So, controlling blood glucose and monitoring renal function are helpful to prevent the occurrence and progress of cognitive dysfunction.