Nonsurgical periodontal therapy remodels oral microbiome-metabolome networks and associates with glycemic and inflammatory improvements in type 2 diabetes mellitus with periodontitis: a 6-month longitudinal study

Background Periodontitis and type 2 diabetes mellitus (T2DM) have a bidirectional relationship, yet how nonsurgical periodontal therapy (NSPT) affects oral microbiome-metabolome interactions in this comorbidity remains unclear.Objective To longitudinally characterize oral microbiome and metabolome shifts following NSPT in patients with T2DM and periodontitis, and to relate these shifts to periodontal and systemic outcomes.Design A total of 42 participants completed the 6-month follow-up. At baseline, they were randomly assigned to NSPT (supragingival scaling plus scaling and root planning, n = 24) or supragingival scaling alone (n = 18). Periodontal parameters, glycated hemoglobin (HbA1c), C-reactive protein (CRP), and glucose/lipid markers were measured at baseline, at 3 and 6 months. Oral samples were collected at each visit for microbiome profiling and metabolomics. Microbe-metabolite-clinical features and associations were explored using correlation analyses and pathway annotation.Results NSPT improved periodontal inflammation and was accompanied by favorable changes in systemic inflammation and glucose/lipid indices; HbA1c reduction was more pronounced in those with poorer baseline glycemic control. Both groups showed temporal variability in microbiome and metabolome profiles, but the taxa/metabolites that changed differed between groups. Changes in bleeding index correlated positively with 13-eicosenoic acid, xylose, Rothia aeria, and Alloprevotella tannerae, whereas changes in CRP correlated positively with sorbitol, galactitol, Prevotella nigrescens, and Treponema denticola. Selected microbe-metabolite pairs mapped to glutathione and purine metabolism.Conclusion NSPT reshapes oral microbe-metabolite networks in T2DM with periodontitis, implicating redox-related pathways that may link periodontal therapy to systemic inflammation and glycemic control.