Noteworthy, significant correlations between ferritin and glucose (r = 0.39, p = 0.0041), HbA1c (r = 0.46, p = 0.0027), and insulin levels (r = 0.34, p = 0.018) (Supplementary Figure S1) were found, denoting an association between iron and glucose homeostasis in obesity-associated insulin resistance. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.