Insulin resistance as a mediator between obesity and periodontitis risk

Obesity is a well-established risk factor for periodontitis, a chronic inflammatory disease with systemic implications. While diabetes has been proposed as a potential mediator in this relationship, its clinical heterogeneity limits its utility in causal modeling. Insulin resistance, quantified by the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), offers a more mechanistically grounded alternative.

This study aimed to investigate the associations between obesity, insulin resistance, and periodontitis, with a specific focus on the mediating role of HOMA-IR.

Data from the National Health and Nutrition Examination Survey (NHANES, 2009-2012) including 8,473 participants were analyzed. Obesity was assessed using body mass index (BMI) and waist circumference (WC), and insulin resistance was measured using HOMA-IR. Periodontitis was evaluated using clinical attachment loss and probing depth. Multivariable logistic regression, restricted cubic splines, and mediation analyses were conducted.

Both BMI and WC were significantly associated with an increased risk of periodontitis (P < 0.05). HOMA-IR was positively associated with periodontitis risk (P < 0.01). Mediation analysis revealed that HOMA-IR mediated 63.44% of the association between BMI and periodontitis and 36.77% of that between WC and periodontitis. Nonlinear analyses showed no significant nonlinear trends.

Insulin resistance, as reflected by HOMA-IR, plays a significant mediating role in the relationship between obesity and periodontitis. These findings underscore the importance of early metabolic regulation in mitigating obesity-related periodontal risk and provide mechanistic insight into the interplay between systemic and oral health.