TNF and rheumatoid arthritis: There are inconsistencies regarding the prevalence of DM in RA, however the previous research support the increased prevalence of DM or insulin resistance in RA in many instances, caused by immune system activation and/or RA treatment.[19,20] Tumor necrosis factor alpha (TNF-a) is a mediator of insulin resistance and has a major role in the pathogenesis of RA.[21,22] Additionally, TNF-a inhibitors reduces the risk of developing DM in RA patients, in which emphasizes the involvement of TNF-a in the common pathogenesis between RA and DM.[23]