Periodontitis is associated with aggravation of prediabetes in Zucker fatty rats

Background: Prediabetes is part of the natural history of type 2 diabetes. Few human studies have addressed the relationship between periodontitis and prediabetes. The Zucker fatty rat (ZFR) is a known model of prediabetes, characterized by hyperinsulinemia, dyslipidemia, and moderate hypertension. The aim of the present study was to investigate whether periodontitis affects the prediabetic state of ZFRs. Methods: Male adult ZFRs (fa/fa; N = 24) and their lean littermates (+/fa; N = 24) were studied. Periodontitis was induced with ligatures in half of the ZFRs and lean rats, whereas the other half served as controls. After 4 weeks, body weight, food intake, glucose tolerance, insulin resistance, free fatty acids, cytokines, and alveolar bone loss were recorded. Results: ZFRs with periodontitis presented increased glucose intolerance (P = 0.03) and a slight increase in fasting glucose from initial to final evaluation, as detected through paired analysis (P = 0.03). Among lean rats, those with periodontitis presented higher final glucose intolerance than those without periodontitis (P = 0.01). Furthermore, periodontitis in lean rats was associated with increased fasting glucose, insulin, and insulin resistance, as evaluated through paired analysis (P = 0.003, P = 0.008, and P = 0.001, respectively). Regarding alveolar bone analysis, ZFRs with periodontitis demonstrated significantly more bone loss compared to lean rats with periodontitis (P < 0.001). Conclusions: Prediabetes worsened periodontitis, and periodontitis, in turn, was associated with deterioration of glucose metabolism in ZFRs, suggesting a progress toward diabetes. Furthermore, periodontitis also affected glucose regulation in lean rats.