Irisin serum levels were reported to be associated with an increased cardio metabolic risk 16, and the circulating level of irisin was found to be higher in patients with type 1 diabetes mellitus (T1DM) than in healthy people and notably lower in younger patients with myocardial infarction (MI) 17, 18; MI has been shown to be associated with a decrease in serum irisin levels 19. Here, FNDC5 is linked to type 1 diabetes mellitus.