Diabetes in mouse models of insulin resistance, insulin deficiency, and obesity can be reversed by the overexpression of Igfbp2 (Hedbacker et al., 2010) and, in contrast, mice harboring a mutation in Lep become obese and diabetic (Zhang et al., 1994). The gene discussed is IGFBP2; the disease is obesity due to melanocortin 4 receptor deficiency.