Abstract: Type 2 diabetes mellitus（T2DM）is an endocrine disease with high prevalence，and chronic periodontitis（CP）is a common oral disease with high incidence. A number of studies have shown that the two are closely related in clinical manifestations. In recent years，researchers have gradually revealed the status of oral microbiota in patients with T2DM and CP through experiments at the microbial level，trying to explore the law of disease in patients with T2DM and CP. However，there is no systematic introduction to the diversity and specificity of oral microbiota in patients with T2DM and CP. Based on the clinical correlation，this article elaborates the relationship between the two diseases and oral microbiota，and further reviews the research progress of the oral microenvironment of T2DM patients with CP according to the rapid development and update of experimental methods in microbiology，so as to provide the direction for further research. 

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