RETN and obesity due to melanocortin 4 receptor deficiency: Among adipokines, leptin, adiponectin, resistin, and omentin, as well as cytokines and chemokines (TNF-α, IL-6), result in chronic inflammation, which may play a key role in the development of insulin resistance and T2DM and increase the risk of obesity-related cardiovascular disease, collectively referred to as the metabolic syndrome (1, 2, 74, 75).