The bidirectional relationship between diabetes mellitus (DM) and periodontal disease (PD) has been increasingly recognized in the literature. DM predisposes individuals to greater risk, prevalence, severity, and progression of periodontitis, while periodontitis adversely affects glycemic control and may exacerbate diabetes. This review synthesizes epidemiological evidence from cohort and cross-sectional studies, explores molecular and immunoinflammatory mechanisms, and discusses clinical implications, including periodontal therapy’s impact on glycemic parameters. A systematic search was conducted in major databases, yielding high-quality observational and mechanistic studies. Meta-analytic data indicate that individuals with periodontitis have a ~1.26-fold increased risk of developing diabetes, and diabetics have a ~1.24-fold increased risk of incident periodontitis. Mechanistically, advanced glycation end products (AGEs), chronic inflammation, altered host response, insulin resistance, and dysbiosis link the two conditions. Periodontal treatment has shown modest but clinically meaningful reductions in HbA1c. These findings emphasize the need for integrated medical-dental care and further high-quality interventional trials.

Keywords: diabetes mellitus; periodontal disease; periodontitis; inflammation; advanced glycation end products; glycemic control