Abstract. The relationship between diabetes mellitus and periodontal disease is among the most thoroughly documented connections in oral-systemic medicine. Decades of epidemiological, clinical, and mechanistic research have established that the association operates in both directions: diabetes increases the risk, severity, and progression of periodontitis, while periodontal inflammation impairs glycemic control and may increase the risk of developing type 2 diabetes and its complications. Periodontitis is now widely recognized as the sixth complication of diabetes, and major diabetes and periodontal professional organizations recommend coordinated screening and management. This review summarizes the key findings and their clinical implications.
Key Findings from the Literature
Large population studies, including analyses of National Health and Nutrition Examination Survey (NHANES) data, consistently show that adults with diabetes have approximately two to three times the risk of periodontitis compared with non-diabetic individuals. Risk rises with poorer glycemic control: patients with HbA1c above 9% show significantly more severe attachment loss and tooth loss than well-controlled patients.
The reverse direction is equally significant. A landmark series of meta-analyses prepared for the joint workshop of the European Federation of Periodontology (EFP) and the International Diabetes Federation (IDF) concluded that severe periodontitis is associated with higher HbA1c in people with and without diabetes, and with an increased incidence of type 2 diabetes. Intervention studies provide the most compelling evidence: a Cochrane systematic review found that non-surgical periodontal therapy (scaling and root planing) reduces HbA1c by approximately 0.3 to 0.4 percentage points at three to four months — a clinically meaningful reduction comparable to adding a second medication for some patients.
Patients with diabetes and severe periodontitis also show higher rates of diabetic complications, including nephropathy, retinopathy, and cardiovascular events, compared with diabetic patients with healthy periodontium.
Proposed Biological Mechanisms
1. Hyperglycemia and Advanced Glycation End Products
Sustained hyperglycemia drives the formation of advanced glycation end products (AGEs), which accumulate in periodontal tissues. AGE binding to its receptor (RAGE) on macrophages and endothelial cells amplifies local inflammatory cytokine production (IL-1β, IL-6, TNF-α), impairs neutrophil function, and compromises collagen turnover — collectively accelerating periodontal tissue destruction and impairing healing.
2. Systemic Inflammatory Burden
Chronic periodontitis releases bacterial products and inflammatory mediators into the circulation. Elevated circulating TNF-α and IL-6 interfere with insulin receptor signaling, promoting insulin resistance. This explains how periodontal inflammation can worsen glycemic control even in patients without diagnosed diabetes.
3. Altered Wound Healing and Microvascular Changes
Diabetes-associated microangiopathy reduces perfusion of gingival tissues, while impaired fibroblast and osteoblast function compromises the periodontium’s capacity for repair, making tissues both more susceptible to breakdown and slower to respond to therapy.
Clinical Implications
The evidence supports an integrated model of care. Patients with diabetes should receive regular periodontal evaluation — at minimum annually, and more frequently when glycemic control is suboptimal. Conversely, patients presenting with severe or refractory periodontitis and risk factors for diabetes are reasonable candidates for chairside HbA1c screening or referral for medical evaluation; studies suggest dental practices can identify substantial numbers of patients with undiagnosed dysglycemia.
For patients managing diabetes, periodontal therapy should be framed not only as oral health care but as a component of metabolic management. The 0.3–0.4 point HbA1c reduction achievable with periodontal treatment is associated, in epidemiological models, with meaningful reductions in microvascular complication risk.
At Fridman Family Dental Care, we coordinate with our patients’ physicians when periodontal findings suggest systemic involvement, and we encourage patients with diabetes to share their most recent HbA1c values so we can tailor recall intervals and treatment planning accordingly.
References
Sanz M, Ceriello A, Buysschaert M, et al. Scientific evidence on the links between periodontal diseases and diabetes: Consensus report and guidelines of the joint workshop on periodontal diseases and diabetes by the International Diabetes Federation and the European Federation of Periodontology. J Clin Periodontol. 2018;45(2):138-149.
Simpson TC, Clarkson JE, Worthington HV, et al. Treatment of periodontitis for glycaemic control in people with diabetes mellitus. Cochrane Database Syst Rev. 2022;4:CD004714.
Löe H. Periodontal disease: the sixth complication of diabetes mellitus. Diabetes Care. 1993;16(1):329-334.
Graziani F, Gennai S, Solini A, Petrini M. A systematic review and meta-analysis of epidemiologic observational evidence on the effect of periodontitis on diabetes. J Clin Periodontol. 2018;45(2):167-187.
Concerned about how gum health may be affecting your diabetes — or vice versa? The team at Fridman Family Dental Care in Valencia, CA is happy to help. Contact us to request an appointment.
