In turn, hyperglycemia converts Treg cells to Th1 or Th17 cells, thereby exacerbating this imbalance (Zhang et al., 2021a) and impairing defense systems in periodontal tissue via the release of inflammatory factors, such as IL-17, to significantly increase periodontitis risk and severity (Huang et al., 2020a). The gene discussed is IL17A; the disease is periodontitis.