Previous studies found that the activity oftranscriptional co-activator PPAR-γ co-activator-1 α (PGC1α), a molecule up-stream of irisin, in skeletal muscles and therefore circulating irisin level was lower in patients with type 2 diabetes or pre-diabetes than healthy obese subjects [20–22]. The gene discussed is PPARGC1A; the disease is type 2 diabetes mellitus.