DPP4 and type 1 diabetes mellitus: The antidiabetic activity of flavonoids acts on targets involved in type 2 diabetes mellitus, such as aldose reductase, α-glucosidase, and DPP-4 [52], and in insulin-dependent diabetes mellitus, the flavonoid compound quercetin has been reported to increase insulin release by increasing the regeneration of pancreatic islet cells [53].