Oral Microbiota and Type 2 Diabetes: Interactions, Potential Mechanisms, and Preventive Strategies

The oral cavity harbors the second-largest and one of the most diverse microbial communities in the human body, playing a critical role in maintaining local and systemic health. Type 2 diabetes mellitus (T2DM), a chronic metabolic disease accounting for nearly 90% of all diabetes cases, has shown rapidly increasing global prevalence. Growing clinical and experimental evidence indicates a strong bidirectional relationship between oral microbiota dysbiosis and T2DM. Imbalanced oral microbial communities can contribute to systemic inflammation, insulin resistance, and metabolic dysregulation, while hyperglycemia and impaired immunity in T2DM promote oral diseases such as periodontitis, xerostomia, and mucosal infections. This review summarizes current research on the interactions between oral microbiota and T2DM, highlighting their clinical correlations, underlying mechanisms, and mutual influences on inflammation, microbial composition, and metabolic pathways. We also discuss emerging strategies for T2DM prevention and management through oral microbiota modulation. These insights may provide new perspectives for early diagnosis, targeted intervention, and integrative management of T2DM.