In model 1 (adjustment for sex and age), increase of serum irisin was associated with reduced risks of raised FPG and MetS, the adjusted ORs (95%CI) of per standard deviation (SD) increase of log-transformed serum irisin were 0.870 (0.767–0.987, p = 0.031) and 0.872 (0.768–0.992, p = 0.037), respectively. Here, FNDC5 is linked to metabolic syndrome.