On the other hand, Trp and phenylalanine interact with the GPR142 receptor, increasing insulin secretion and the incretins GIP and GLP-1, improving circulating glucose levels [136], suggesting that the decrease in Trp during obesity will decrease insulin secretion and contribute to the progression to T2D of subjects with obesity. The gene discussed is GCG; the disease is obesity due to melanocortin 4 receptor deficiency.