TGFB1 and diabetic kidney disease: This indicates that concentration plays a crucial role in this regard: high concentrations of dihydrotestosterone (DHT), the most biologically active form of testosterone, stimulate TGF-β1 production and promote DKD in animal models, while a low concentration of DHT, surprisingly, lowers renal TGF-β1 levels and significantly improves the expression of DKD [118].