Series of studies have tested the role of potential islet differentiation triggers such as glucagon-like peptide 1 (GLP-1)10, cholecystokinin (CCK)11 and insulin-like growth factor-1 (IGF-1)12 in promoting maturation of fetal islet-bearing grafts either in vitro13,14 or in vivo11,15 aiming to shorten the latent period between Tx and reversal of hyperglycemia. This evidence concerns the gene GCG and Hyperglycemia.