Objective To explore the effect of dietary knowledge of diabetes on the readmission rate on patients with type 2 diabetes mellitus. Methods Totally 334 patients of type 2 diabetes from Suzhou finished the general information and the questionnaires of knowledge of diabetes diet. The impacts of knowledge of diabetes dietary on their readmission rates were also analyzed. Results Both whether having hypoglycemia or not and the score of diabetes dietary knowledge were associated with readmission rate within half a year. Those having low blood sugar (B=1.276, P<0.01) and higher score of diabetes dietary knowledge (B = 0.049, P = 0.006) had higher readmission rate. Further analysis showed that patients with low blood sugar getting higher score of diabetes dietary knowledge had higher hospital admission rate (P = 0.01). Conclusions The readmission rate of type 2 diabetes mellitus patients was impacted by hypoglycemia occurrence and the familiarity degree of diabetes diet knowledge. So it′s important to further explore the causes and make the reasonable intervention to reduce the readmission rate.