These mice have lifelong hyperglycemia and hyperinsulinemia; over time, hyperglycemia worsens and blood insulin declines, with early‐stage β‐cell dedifferentiation apparent at 16–20 weeks (Gómez‐Banoy et al., 2019; Ishida et al., 2017; John et al., 2018; Sinha et al., 1979). This evidence concerns the gene INS and hyperinsulinism.