Association between Periodontal Disease and Diabetes Mellitus: A Systematic review

Background: Periodontal disease and diabetes mellitus are chronic inflammatory conditions that frequently coexist and may influence each other through shared pathogenic mechanisms. Growing evidence suggests a bidirectional relationship, with potential implications for glycaemic control, periodontal outcomes, and diabetes-related complications. This systematic review aimed to synthesize recent evidence on the association between periodontal disease and diabetes mellitus, including therapeutic, complication-related, mechanistic, and Indian population-based data. Material and methods: A systematic review was conducted in accordance with PRISMA 2020 guidelines. Electronic searches of PubMed/MEDLINE, Scopus, and Web of Science, supplemented by manual reference screening, identified eligible studies published up to June 2025. Studies were included if they evaluated the association between periodontal disease and diabetes, the effect of periodontal therapy on metabolic outcomes, diabetes-related complications, or mechanistic and population-based evidence. Sixteen studies meeting predefined eligibility criteria were included and categorized into four evidence domains. Data were synthesized narratively. Results: Longitudinal and population-based studies demonstrated a bidirectional association between periodontal disease and diabetes mellitus, indicating increased risk of each condition in the presence of the other. Interventional and synthesis-level evidence showed that non-surgical periodontal therapy was associated with improvements in periodontal parameters and glycaemic control, with adjunctive therapies providing additional benefit in some studies. Evidence from cohort and meta-analytic studies linked periodontitis with a higher risk of diabetes-related complications, particularly microvascular outcomes. Mechanistic studies supported biological plausibility through shared inflammatory and immune pathways, while Indian population-based studies consistently reported a higher prevalence and severity of periodontal disease among individuals with diabetes. Conclusion: The available evidence supports a clinically meaningful, bidirectional association between periodontal disease and diabetes mellitus. Integrating periodontal care into diabetes management may contribute to improved metabolic control and reduced complication risk