Integrative analysis of bacterial diversity in patients with type 2 diabetes mellitus and periodontitis using a case-control microbiome approach.

AIM: Type 2 diabetes mellitus (T2DM) is a risk factor for periodontitis; however, its relationship with the oral microbiome remains poorly defined. Here, we characterize taxonomic composition and predicted microbial functions in the salivary microbiome of T2DM and non-diabetic patients with periodontitis, while evaluating the influence of disease stage, smoking, and sex.

METHODS AND

RESULTS

We analyzed saliva from 100 periodontitis patients (50 T2DM, 50 non-diabetic controls) using 16S rRNA V3-V4 sequencing, selecting a screened, deliberately balanced cohort to ensure robust comparison. α-diversity did not differ significantly across diabetes status, disease stage, smoking, or sex. However, β-diversity analysis revealed a statistically significant differences in microbial community composition between T2DM and non-diabetic controls (R2 = 0.016, p = 0.029). Differential abundance analysis showed enrichment of Neisseria (p = 0.02, Wilcoxon test with Bonferroni correction) and Corynebacterium matruchotii (p = 0.002) in T2DM patients, whereas Haemophilus sputorum was enriched in mild periodontitis. Among smokers, Neisseria elongata (p = 0.009) was more abundant than in non-smokers. Female patients exhibited higher abundances of Haemophilus, Neisseria, Gemella, Aggregatibacter, Corynebacterium, and Cardiobacterium (p < 0.02), whereas Megasphaera was enriched in males (p = 0.04). PICRUSt-based predictions indicated TDM2-associated enrichment of pathway related to virulence, nutrient acquisition, and pyridoxal-5'-phosphate biosynthesis, particularly in moderate and severe periodontitis.

CONCLUSIONS

T2DM is associated with distinct shifts in salivary microbial composition and predicted function, revealing taxa and pathways linked to periodontitis.