In particular, sDPP-4 has been considered a key factor connecting obesity with inflammation and insulin resistance; DPP-4 regulates adipokines, as leptin and adiponectin, and a negative correlation between blood DPP-4 activity and circulating adiponectin levels in lean and obese subjects has been observed [48,49]. Here, DPP4 is linked to obesity due to melanocortin 4 receptor deficiency.