Enhanced β-cell proliferation occurs naturally during pregnancy [5, 7] as well as obesity induced states of insulin resistance [8, 9].The recent discovery of betatrophin as a potential inducer of β-cell proliferation in mice in response to insulin resistance has revived the hope for achieving this goal [10, 11]. The gene discussed is ANGPTL8; the disease is obesity due to melanocortin 4 receptor deficiency.