Insulin has been widely used to treat diabetes and its complications, and it can regulate DCM through multiple pathways, including its involvement in regulating excessive production of advanced glycation end-products; activating the hexosamine biosynthetic pathway; ameliorating the effects of lipotoxicity, mitochondrial dysfunction, and increased oxidative stress; activating the renin–angiotensin system; and restoring impaired calcium homeostasis [56]. The gene discussed is REN; the disease is diabetes mellitus.