Despite great advances during the last decade, each of these molecular targets may not be ideal as BCM markers in human, GLP-1R expression in acinar pancreas is highly variable between species [18] and this may account for the background binding of [68Ga]Exendin4 seen also in human subjects with T1D; [11C]5-Hydroxy-tryptophan is a general endocrine marker and will thus depict both alpha and beta cells in pancreas; and VMAT2 targeting radioligands exhibit a relatively high acinar background binding in most species, including humans, potentially decreasing sensitivity [1]. The gene discussed is GLP1R; the disease is type 1 diabetes mellitus.