Quercetin stimulates glucose uptake by regulating mitogen-activated protein kinase (MAPK) insulin-dependent mechanisms, improving renal function, inhibiting the overexpression of transforming growth factor beta 1 (TGF-β1) and connective tissue growth factor (CTGF), hindering polyol accumulation as well as blocking aldose reductase, and thus reducing joint pain, irritation, and numbness, which are common symptoms observed in diabetes [184]. This evidence concerns the gene TGFB1 and diabetes mellitus.