Didymin inhibited α-glucosidase, activated the insulin-signaling pathway, and improved insulin sensitivity. It showed potent inhibitory activity against the key enzymes involved in diabetes mellitus, including protein tyrosine phosphatase 1B (PTP1B), α- glucosidase, advanced glycation end products (AGEs), and aldose reductase (AR). The gene discussed is AR; the disease is diabetes mellitus.