INS and obesity due to melanocortin 4 receptor deficiency: Moreover, higher levels of dipeptidyl peptidase 4 (DPP-4) in patients with obesity may additionally impair the immune system, with inhibition of DDP-4 improving insulin sensitivity in both obese and non-obese patients, thus potentially suppressing the pro-inflammatory response associated cytokines such as interleukin-10 (IL-10) and IL-6.