Spermidine treatment significantly mitigated these alterations, lowering glucose levels, alleviating histopathological injury, elevating the antioxidant defense (GSH, SOD, CAT, GPx) and the Nrf2 and decreasing MDA and TGF-β concentrations (p < 0.05 vs. Diabetes). The gene discussed is TGFB1; the disease is diabetes mellitus.