White pitaya juice and purified peel betacyanins (PPBNs) improved insulin resistance through decreasing fibroblast growth factor-21 (FGF-21) expression and increasing level of FGF-21 related genes (Klb, FGFR2, Egr1 and cFos) in the liver [9, 27]. The gene discussed is FGF21; the disease is Insulin resistance.