In patients with obesity and without diabetes, the PP protein expression showed a positive correlation with abdominal pain (r = 0.408, p = 0.043; Figure 8a), while DPP-4 protein expression exhibited a positive correlation with indigestion (r = 0.407, p = 0.043; Figure 8b). Here, PPY is linked to obesity due to melanocortin 4 receptor deficiency.