INS and diabetes mellitus: These differentiated cells display architectural similarity to mature primary islets, are capable of synthesizing insulin, glucagon, somatostatin, pancreatic polypeptide and ghrelin [229, 230], reverse hyperglycemia in diabetic mice, prolong graft survival, and respond successfully to glucose challenge in glucose-tolerant tests (GTT) providing definitive evidence of the ability of hESCs to serve as a renewable source of insulin-secreting β-cells for diabetes cell-replacement therapies.