Obesity appears to be associated with a reduced postprandial GLP-2 response [103], possibly due to increased DPP-4 activity [87], which may partly explain the findings of Cazzo et al. In contrast, fasting GLP-2 levels were significantly higher in individuals with obesity compared to lean individuals in two other studies [52, 106], while a third study found no difference in fasting GLP-2 levels between individuals with elevated versus normal body weight [105]. The gene discussed is GCG; the disease is obesity due to melanocortin 4 receptor deficiency.