IAPP and type 2 diabetes mellitus: There are now many hIAPP structures that have been solved (Table 2) many to high resolution, including fibrils [103,113–127], monomers [32,128,129], oligomers (tetramers) [130], hIAPP analogues [131], hIAPP in combination with other proteins [117,132–134] and structures of pro-IAPP polypeptide [135], and give some insight into how hIAPP might be linked to T2DM.