DPP4 and obesity due to melanocortin 4 receptor deficiency: In this phenomenon the glucagon-lowering effect of DPP-4 vildagliptin must also be taken into consideration [19] In addition this increased serum DPP-4 activity in NAFLD could not be explained by the degree of obesity and (Table 1) the existing correlation between serum DPP-4 activity and insulin resistance (HOMA2-IR) in NAFLD is not surprising, provided that serum DPP-4 activity is considered as a novel liver disease biomarker.