Betacellulin (BTC) is one of “islets regeneration factors” which received more and more attention these years. BTCe is the C-terminal 50-residue region of mature BTC protein and can bind with erbB-1、erbB-4 receptor. It has the same mitogenic activity on cells as the whole section. BTC and BTCe can improve the level of glucose-stimulated insulin secretion (GSIS) during islets culture in vitro though they had no effect on the acute insulin secretion. BTCe also effectively ameliorated the hyperglycemia of STZ-induced diabetic rats by a single plasmid injection into muscle of rats. It is supposed that BTCe promote the proliferation of PDX-1 positive cells or repair some signal transduction pathway. Perhaps the latter is more important.