NAMPT and type 2 diabetes mellitus: Metabolic inflammation involves increased expression of adipokines such as leptin and visfatin as well as proinflammatory cytokines such as interleukin 1-β (IL-1β), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8), and interleukin 12 (IL-12), most of which are implicated in insulin resistance and type 2 diabetes (T2D) [3,4].