Insulin resistance and periodontitis: Mediation by blood pressure.

Aim: This study investigated the association between the triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, and moderate/severe periodontitis and the role of blood pressure as a mediator in this association. A second aim was to assess the role of cardiometabolic conditions such as obesity, hypertension, and dyslipidemia as potential effect modifiers.

Methods: Data from 5733 US adults aged 30-64 years and with complete periodontal examination were analyzed (NHANES 2011-2014). Participants were classified as having moderate/severe periodontitis or mild/no periodontitis according to the CDC/AAP criteria as the outcome. The exposure was the TyG index, while both systolic (SBP), and diastolic (DBP) blood pressure were tested as mediators using parametric g-formula. Analyses were adjusted for relevant confounders, namely, age, sex, ethnicity, poverty-income ratio, and smoking, using inverse probability treatment weighting. Obesity status (based on a body mass index ≥30 kg/m²), self-report of hypertension and dyslipidemia (calculated based on the thresholds provided by National Cholesterol Education Program-Adult Treatment Panel-III) were tested as effect modifiers.

Results: The findings showed the TyG index to be associated with increased odds of moderate/severe periodontitis [odds ratio (OR), 95% confidence interval (CI) = 1.17 (1.11-1.23)], with 50% of the total effect mediated by SBP. Stratified analysis showed a stronger association in individuals with obesity, hypertension, and dyslipidemia compared to those without these conditions. However, in those taking anti-hypertensive medications, the association was partially mitigated. Sensitivity analysis using imputed data showed consistent results.

Conclusion: The TyG index was associated with increased odds of moderate/severe periodontitis, especially in individuals with obesity, hypertension, and dyslipidemia. SBP levels partially mediated this association.