Kowalska et al. [32] reported lower insulin sensitivity in both lean and obese PCOS patients, but increased serum visfatin levels only in lean PCOS women with a negative correlation with insulin sensitivity and a positive correlation with markers of hyperandrogenism, suggesting that obesity may deregulate visfatin expression and that other factors may be involved in this process. This evidence concerns the gene NAMPT and obesity due to melanocortin 4 receptor deficiency.