Accumulating evidence suggests this may be impaired β-cell metabolism, as changes in metabolic genes, or in metabolism, have been identified in islets isolated from T2D donors19,20, control human islets cultured at 25 mM glucose3, diabetic GK rat islets21, mouse models of diabetes22–24 and insulin-secreting cell lines exposed to high glucose4,5. This evidence concerns the gene INS and type 2 diabetes mellitus.