We previously generated transgenic mice overexpressing PACAP in pancreatic β cells under the control of human insulin promoter (PACAP-Tg), and reported that PACAP-Tg mice show ameliorated streptozotocin-induced type 1 diabetes [12], normalized hyperplasia of pancreatic islets, and attenuated hyperinsulinemia in mouse models of type 2 diabetes such as KKAy mice and high-fat diet feeding [3], [4], [13], [14]. This evidence concerns the gene ADCYAP1 and hyperinsulinism.