Imeglimin suppresses glucagon secretion and induces a loss of α cell identity

Dysregulated α cell function contributes to the development of diabetes. In this study, we find that treatment with imeglimin, an antidiabetic drug, prevents glucagon release and induces a loss of α cell identity through direct action on α cells. Mechanistically, imeglimin reduces Gsα expression to inhibit the exchange protein directly activated by cyclic adenosine monophosphate 2 (EPAC2)-mediated secretion of glucagon induced by low glucose, gastric inhibitory polypeptide (GIP), or adrenaline in an insulin-independent manner. Imeglimin also attenuates α cell Ca2+ oscillations. MafB expression is downregulated by imeglimin to induce α cell dedifferentiation. In addition, imeglimin upregulates C/EBP homologous protein (CHOP) expression, which partly contributes to the reduction in Gsα and MafB expression to reduce glucagon secretion and induce α cell reprogramming without altering protein translation. These pleiotropic effects of imeglimin on glucagon secretion and α cell identity can be recapitulated in mouse models of diabetes in vivo. These data suggest that the imeglimin-mediated regulation of α cell plasticity, particularly via glucagon suppression, may contribute to glucose homeostasis.