IL21 and periodontitis: As found in the present study, in T2DM patients with periodontitis, statins treatment reduced pro-inflammatory factors IFN-γ, IL-1β, IL-2, IL-6, IL-7, IL-21 and TNF-α levels in GCF, and enhanced anti-inflammatory factors IL-4 and IL-5 levels through the anti-inflammation and anti-oxidation effects [46].