AKR1B1 and diabetes mellitus: Considering the inhibitory effects of other plants such as tea leaves [64], Zingiber officinale [65], and Phyllostachys nigra [66] on aldose reductase, the antioxidant properties of walnut leaves, and our finding regarding the decrease of aldose reductase activity and distribution in the testicular tissue of the treatment groups, it can be proposed that the flavonoid antioxidants of walnut leaves can reduce diabetic oxidative stress through alteration of the polyol pathway, which may prevent or delay some of the important complications of diabetes mellitus.