After 2 months, almost all the islets in the 90% depancreatized control rats were destroyed, whereas the islets of the remaining pancreas in the Reg protein-treated rats were enlarged and almost entirely stained for insulin.169) Human REG protein administration also ameliorated diabetes in NOD mice with an increase in the β-cell mass.170) These results indicate that Reg protein stimulates the regeneration and/or growth of pancreatic β-cells, thereby ameliorating animal diabetes. Here, REG1A is linked to diabetes mellitus.