Objective To study the application effect of periodontal foundation therapy in patients with chronic periodontitis and type 2 diabetes mellitus. Methods From March 2020 to 2021, 80 patients with chronic periodontitis complicated with type 2 diabetes mellitus treated into Sanming Integrated Medicine Hospital from March 2020 to March 2021 were selected as the research objects. They were divided into the control group (40 cases) and the intervention group (40 cases) according to ballot methods. The control group was treated with Ornidazole Tablets and Cefaclor, while the intervention group was treated with periodontal basic therapy on the basis of the control group. The periodontal treatment indexes (sulcus bleeding index [SBI] and periodontal probing depth [PD]) and the inflammatory factor index(tumor necrosis factor-α [TNF-α] and high sensitive C-reactive protein [hs-CRP]) and blood glucose index (fasting blood glucose and 2-hour postprandial blood glucose level) were compared between the two groups. Results The levels of SBI and PD in the intervention group were lower than those in the control group, the differences were statistically significant (P＜0.05). The levels of TNF-α and hs-CRP in the intervention group were lower than those in the control group, the differences were statistically significant (P＜0.05). The fasting blood glucose level and 2-hour postprandial blood glucose level in the intervention group were lower than those in the control group, the differences were statistically significant (P＜0.05). Conclusion The application effect of periodontal basic therapy is effective in patients with chronic periodontitis and type 2 diabetes mellitus. It can effectively relieve and eliminate periodontal diseases, reduce inflammatory factors, and reduce blood glucose level, promote blood glucose control, improve physical and mental health and quality of life, and is worthy of popularization and application.