Jejunal EECs isolated from patients with T2DM also demonstrate downregulation in genes involved in EEC differentiation (including PAX4 and FOXA2) and in the GCG gene itself (42), indicating that jejunal GLP-1+ cell differentiation and number are negatively affected by both obesity and T2DM. Here, GLP1R is linked to obesity due to melanocortin 4 receptor deficiency.