Male IRS2-deficient mice (IRS2−/−) are used as a type 2 diabetes model because they exhibit defects in hepatic insulin signalling, resulting in impaired suppression of glucose production (Withers et al., 1998; Kubota et al., 2000; Previs et al., 2000), and β-cell failure due to disruption of the IGF-I receptor (IGF-IR) mitogenic signalling (Withers et al., 1999) and increased β-cell apoptosis (Lingohr et al., 2003). The gene discussed is IGF1R; the disease is type 2 diabetes mellitus.