To investigate the potential role of irisin and leptin as markers of diabetes, Sahin-Efe et al. [42] measured the serum levels of irisin in stored blood samples of non-obese, obese, non-obese that, years after, had been diagnosed with diabetes type II, and observed that both leptin and irisin were significantly higher in obese subjects. This evidence concerns the gene FNDC5 and type 2 diabetes mellitus.