Numerous studies have attempted to identify several mechanisms linking obesity with insulin resistance and type 2 diabetes, and factors have been suggested to play in obesity-related insulin resistance such as tumour necrosis factor-α(TNF-α), interleukin-6 (IL-6), non-esterified fatty acids (NEFA), resistin and adiponectin [1]. Here, RETN is linked to obesity due to melanocortin 4 receptor deficiency.