Purpose: To explore the relationship between cognitive impairment and insulin resistance (IR) in elderly patients with type-2 diabetes mellitus. Materials and methods: Two hundred and twelve elderly patients with type-2 diabetes were enrolled in this study and assigned into either the cognitive impairment group (n = 100) or the normal cognitive group (n = 112). Gender, age, education, body mass index (BMI), total cholesterol, triglyceride, low-density lipoprotein cholesterol, creatinine (Cr), fasting plasma glucose, fasting insulin (FINS) and homeostasis model of assessment for IR index (HOMA-IR) were compared between the two groups. Multifactorial logistic regression analysis was performed. Results: In cognitive impairment group, education level (33.00 vs 53.57%, p < 0.01) was lower, the level of BMI [(28.7 +/- 4.5) kg/m(2) vs (23.9 +/- 3.7) kg/m(2), p < 0.01], FINS [(21.8 +/- 5.3) mU/L vs (12.9 +/- 3.9) mU/L, p < 0.01], HOMA-IR [(6.9 +/- 1.7) vs (3.9 +/- 0.9), p < 0.01] were higher than the control group. In the logistic regression, education level (B = -0.996, p = 0.03), FINS (B = 1.120, p < 0.01) and HOMA-IR (B = 1.301, p < 0.01) were independent factors. Conclusions: Our study demonstrates that the education level, FINS and HOMA-IR were independent factors of cognitive impairment in elderly patients with type-2 diabetes. IR is an important risk factor and higher education level in a protective factor for the cognitive impairment in elderly patients with type-2 diabetes.