One of the common contributors to the failure in the clinical trials is the irreproducibility of the improvement in the treated animal models vs. in humans, for example, sorbinil (an aldose reductase inhibitor), which was shown to inhibit diabetes-induced nerve conduction deficit in streptozotocin-induced diabetic rats [150]; however, it did not produce similar results in humans [151]. This evidence concerns the gene AKR1B1 and diabetes mellitus.