Aim: To explore the differences of cognition function and cognition domain function between patients with diabetes and normal controls, and to make related analysis on the relation between the cognition function score and blood sugar of patients with diabetes. Methods: Dementia expansive scale(ESD) was used as the tool to examine the cognition function of diabetic patients and normal controls, with the method of independent sampling T test, and significance test was performed on cognition function score. Meanwhile, regression analysis was carried out to study the relationship between cognition function score and blood sugar. Results: The universe cognition function score of patients with diabetes (209.59 ± 20.77) was lower than that of normal subjects(224.28 ± 10.56), (t = 4.208, P < 0.001). Meanwhile, the scores in memory abstract and structure field were also lower than those of normal subjects. It suggested from the related regression analysis results that universe cognition function socre, memory ability and glycated ferrohemoglobin had obvious correlations, with the Pearson correlation coefficient of -0.40 (P < 0.05 and -0.329 (P < 0.05) respectively. Conclusion: Diabetic cognitive impairment is significantly related to blood sugar.