PNPLA3 and type 2 diabetes mellitus: These observations raise several questions, for example how a missense variant in PNPLA3 leads to a change in the circulating levels of ARFIP2, if ARFIP2 provides some sort of readout of PNPLA3 function and finally how ARFIP2 relates to type 2 diabetes, i.e., if it mediates any of the risk associated with this locus or if it is merely a bystander.