CD4 and obesity due to melanocortin 4 receptor deficiency: CD4 + T cells can directly or indirectly aggravate IR by secreting IL-17, IFN-γ and other cytokines, which is an important mechanism of IR development and islet β cell damage in T2DM patients.[33,34] Dendritic cells are a group of antigen-presenting cells that secrete immune mediators, cytokines, and chemokines associated with chronic inflammatory diseases.[35] Dendritic cells aggregate in the subcutaneous fat of patients with high fat diet and obesity, and induce pro-inflammatory microenvironment by mediating the production of interleukin-6 (IL-6) by macrophages.