CDKN1B and Hyperglycemia: Since data obtained from experiments using cell lines, fetal islets or islets of knock-out mice to elucidate the role of p27kip1 and glucose on beta cell replication may not be suitable for applying to adult islets, in this study, we used primary islets of adult mice to investigate the complementary role of hyperglycemia and persistent p27kip1 suppression on beta cell regeneration.