FNDC5 and obesity due to melanocortin 4 receptor deficiency: Through the assessment of body weight, body fat, and endothelial cell dysfunction markers, one study found that the increased plasma irisin level in patients with type 2 diabetes was correlated with the levels of obesity indicators, and irisin may be involved in atherosclerotic endothelial injury accompanied by obesity and type 2 diabetes mellitus [26].