Oral microbiota in periodontitis patients with and without type 2 diabetes mellitus and their shifts after the nonsurgical periodontal therapy.

Objective: To investigate the shift in the oral microbiota of periodontitis patients with and without type 2 diabetes mellitus (T2DM) undergoing nonsurgical periodontal treatment and its implications. Methods: Eleven patients with chronic periodontitis and eleven patients with chronic periodontitis and diabetes from the Second Affiliated Hospital of Chongqing Medical University received nonsurgical periodontitis treatment and were re-evaluated 3 months later. DNA from the saliva and subgingival plaques was amplified and sequenced using 16S ribosomal RNA (16S rRNA) gene sequencing for microbiome profiling. Clinical indexes at the onset and after periodontal therapy were recorded and compared. Results: The species richness and dominant microbiota of periodontitis patients with and without T2DM changed significantly after nonsurgical periodontal treatment in both saliva and subgingival plaques. The periodontal condition of the patients was also effectively improved three months after therapy. Glycemic control in patients with periodontitis and T2DM was improved. Additionally, nonsurgical periodontal therapy could increase in subgingival microbial diversity and the proportion of health-associated bacteria but a proportional reduction in pathogenic bacteria in periodontitis patients with T2DM. Network analysis revealed fewer links and a lower level of centralization in the chronic periodontitis (CP) group after treatment. However, more links and a higher network density of the networks were found in the CP + T2DM group, suggesting a more stable microbial community after treatment. Conclusions: There were significant differences in both the structural composition and reaction of the oral microbiota to periodontal treatment between periodontitis patients with and without T2DM. Nonsurgical periodontal treatment can improve metabolic control, decrease the proportion of periodontal pathogens in oral conditions, and help stabilize microbial communities in patients with periodontitis and T2DM. Furthermore, nonsurgical periodontal treatment may be a potential supplementary approach for managing T2DM.