The beneficial effects of phenolic compounds in diabetes have been widely investigated using experimental animal models of T1D (e.g., streptozotocin-induced diabetes) and of T2D (e.g., streptozotocin–nicotinamide diabetic rats, fructose-fed streptozotocin-induced diabetic rats, leptin receptor-deficient Zucker diabetic fatty (ZDF) rats, high-fat-diet-fed rats or fructose-fed rats). This evidence concerns the gene LEPR and diabetes mellitus.