The Relationship Between Diabetes Mellitus and Periodontal Disease: A Bidirectional Clinical Interaction

Background: Diabetes mellitus and periodontitis are common chronic conditions linked by inflammatory, metabolic, behavioral, and socioeconomic factors. Diabetes increases susceptibility to periodontal disease, while periodontal inflammation may worsen glycemic control and contribute to type 2 diabetes progression.Methods: A structured narrative review of literature available through 4 September 2026 was conducted using MEDLINE/PubMed, the Cochrane Library, clinical guidelines, and citation searching. Priority was given to systematic reviews, meta-analyses, randomized trials, prospective studies, consensus reports, and mechanistic research.Results: Diabetes is associated with greater periodontal destruction through hyperglycemia-related immune dysfunction, oxidative stress, advanced glycation end products, impaired tissue repair, and altered bone metabolism. Conversely, periodontitis is associated with poorer glycemic control and a moderately increased risk of type 2 diabetes, potentially through systemic inflammation and impaired insulin signaling. Periodontal therapy improves periodontal health and may modestly reduce glycated hemoglobin, particularly in the short term.Conclusions: Diabetes and periodontitis have a clinically important bidirectional relationship, although evidence is stronger for the effect of diabetes on periodontal disease. Integrated periodontal care, metabolic control, prevention, and collaboration between dental and medical professionals may improve patient outcomes.