The insulin-responsive gene sex hormone-binding globulin (SHBG) links hyperinsulinaemia and altered testosterone concentrations in humans, with genetic studies suggesting a bidirectional relationship between SHBG and metabolic disease (Perry et al., 2010; Semple et al., 2008), yet no orthologue circulates in mouse plasma (Holly and Perks, 2012). The gene discussed is SHBG; the disease is metabolic disease.