TNF and diabetes mellitus: Exactly the same is true of the IL-1 and TNF-α systems in which IL-1 or TNF-α (oxidative stress) acting on one cell can effect the secretion of further IL-1/TNF-α that can act on adjacent cells (Fig 8), of the hypoxia-dependent increase in both ROSs and serum iron mediated by hepcidin (Fig 3), the autocatalytic synergy between overfeeding, inflammation and (pre-)diabetes, and of the peroxide/iron pair that are liberated when frataxin is deficient (see above).