WNT9B and type 2 diabetes mellitus: Wnt9b may play a deleterious role in the development of diabetic foot ulcers, because inhibiting the canonical Wnt9b pathway by circulating exosomal miR‐20b‐5p from T2DM patients is found to suppress the angiogenenic effect of HUVECs in vitro and delay the wound healing in vivo.115