Alteration of subgingival microbiome in patients with type 2 diabetes induced by diabetes treatment

Diabetes and periodontal disease, a bacterial infection involving the oral microbiome, have a bidirectional relationship. However, the relationship between poor glycemic control and the oral microbiome remains unclear. The aim of this study was to assess the direct effect of intensive glycemic control on the oral microbiome in patients with type 2 diabetes mellitus (T2DM).

Twenty-nine patients with T2DM and 29 controls were enrolled in this study. Patients underwent a 2-week intensive glycemic control regimen. We collected subgingival dental plaque and conducted full-length 16S ribosomal RNA gene sequencing to identify bacterial species. The focus was on the subgingival microbiome, particularly 29 species of oral bacteria related to periodontal disease, and the characteristics of the diabetic cohort. Periodontal inflammation was quantified using the periodontal inflamed surface area (PISA).

Prior to diabetes treatment, the relative abundance of Porphyromonas gingivalis (P = 0.018), Tannerella forsythia (P < 0.001), Fusobacterium nucleatum (P = 0.041), and Prevotella intermedia (P < 0.001), known for their high pathogenicity in periodontal disease, was higher in the diabetes group than in the control group. The bacterial species whose relative abundance changed significantly before and after treatment differed between the PISA improved and non-improved groups in patients with diabetes.

Oral bacteria changed pre- and post-diabetes treatment, correlating with improvements in PISA.