Periodontitis and metabolic syndrome

Background + Aims

• Metabolic syndrome (MetS) is a complex condition characterised by impaired glucose metabolism, dyslipidemia, hypertension, and central obesity, doubling the risk of cardiovascular diseases and type 2 diabetes mellitus (T2DM).
• Insulin resistance is considered a central feature of MetS, triggering systemic low-grade inflammation that may increase susceptibility to other inflammatory diseases, including periodontitis.
• Periodontitis is a chronic inflammatory disease involving exaggerated gingival responses to bacterial pathogens, leading to alveolar bone and tooth loss.
• Studies have linked periodontitis to obesity, low-grade inflammation, dyslipidemia, diabetes, and dysmetabolic conditions. Emerging research highlights a potential association between MetS and periodontitis, with insulin resistance proposed as a contributing factor in the pathogenesis of periodontal infections.
• While prior studies have examined the insulin resistance-periodontitis relationship, most were conducted in Western populations, overlooking potential ethnic variations in body composition and fat distribution.
• This study aims to investigate the association between insulin resistance and periodontitis in Korean adults using the homeostasis model assessment (HOMA).

Materials + Methods

• This study utilised data from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted between 2008 and 2010. KNHANES is a nationally representative, cross-sectional survey of the Korean non-institutionalised civilian population.
• The study design employed a stratified, multistage probability sampling method and included a health interview, health examination, and nutrition survey administered by trained personnel.
• Participants ≥19 years old and over who completed all survey components, including a periodontal examination, were included. Subjects with diabetes mellitus or missing fasting plasma glucose or serum insulin data were excluded, resulting in a final sample of 16,720 participants (7060 men and 9660 women).
• Sociodemographic and lifestyle data were collected through self-reported questionnaires, including age, education level, household income, smoking status, alcohol consumption, and physical activity.
• Clinical measurements included body mass index (BMI), waist circumference, blood pressure, fasting glucose, insulin levels, and lipid profiles.
• Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR), with participants in the highest HOMA-IR quartile classified as insulin-resistant.
• Periodontal health was evaluated using the World Health Organization (WHO) Community Periodontal Index (CPI), with periodontitis defined as a CPI score of 3 or 4, indicating pockets ≥3.5 mm.
• Multivariable logistic regression analyses were used to examine the association between insulin resistance and periodontitis, adjusting for confounding factors, with statistical significance set at p<0.05.

Results

• The prevalence of periodontitis was higher in men (27.0%) compared to pre-menopausal women (13.1%) and nearly equal to post-menopausal women (23.8%).
• In both genders, periodontitis prevalence increased with age, peaking among those aged 50 – 59 years before declining.
• Among post-menopausal women, periodontitis prevalence was highest in the top HOMA-IR quartile (27.8%), with a statistically significant trend across quartiles (p = 0.019). No such trend was observed in men or pre-menopausal women.
• Sociodemographic and lifestyle factors, including age, education, income, and oral hygiene practices, varied significantly between periodontitis and non-periodontitis groups across gender and menopausal status.
• Multivariable logistic regression revealed that post-menopausal women in the highest HOMA-IR quartile were significantly more likely to have periodontitis than those in the lowest quartile (adjusted OR 1.47, 95% CI 1.07–2.01).
  • Obesity further amplified the association between insulin resistance and periodontitis in post-menopausal women, with an adjusted OR of 1.92 (95% CI 1.29–2.87).
  • No such interaction was found in men or pre-menopausal women.

Limitations