In modern Chinese society, the incidence of both diabetes and periodontal disease is relatively high and should be taken seriously enough. Diabetes mellitus is an endocrine abnormality associated with several genetic factors. Periodontal disease is a chronic infectious disease that occurs in the periodontal tissues and is caused by plaque bacteria. Both have some degree of abnormal immune regulation. On the one hand, periodontitis has been cited as the sixth complication of diabetes (the other five being vasculopathy, retinopathy, nephropathy, neurological lesions and infected bodies), and on the other hand, over the years, there has been a large number of studies that have demonstrated diabetes to be an important risk factor for periodontal disease. There is a bidirectional relationship between the two: not only does diabetes affect periodontal disease, but periodontal infection in turn affects endocrine metabolism, which affects glycemic control as well as increasing the risk of diabetes-associated conditions. The pathogenesis of diabetes mellitus associated periodontal disease may be due to defects in leukocyte chemotaxis and phagocytosis, alterations in the vascular basement membrane of tissues, decreased collagen synthesis, decreased bone matrix formation, and decreased immunomodulation, which results in decreased resistance to infection and impaired wound healing. Diabetes mellitus has a significant impact on the vascular system, inflammatory response, and tissue repair, thus altering the individual’s response to plaque bacteria, affecting the clinical manifestations of periodontal disease, the pathological process, and the response to periodontal therapy. On the other hand, diabetic patients with severe periodontitis have far less glycemic control than those without periodontitis. Thorough and effective periodontal treatment not only reduces periodontal lesions, but also significantly lowers glycated hemoglobin levels in diabetic patients and reduces insulin resistance in patients with severe diabetes, thereby improving glycemic control and patient condition. Therefore, prevention and treatment of periodontal disease is an important part of diabetes control. In conclusion, diabetic patients must diligently monitor their blood glucose, and on the basis of glycemic control and anti-inflammation, actively carry out systematic and standardized treatment of periodontal disease.