The CSF levels in AD and AD+T2D remained unaltered compared to NC when plasma levels of unmodified IAPP were included as a covariate (p = 0.899) and the ratio between plasma IAPP levels and CSF IAPP levels did not differ between AD patients, AD+T2D patients and NCs (p = 0.482). Here, IAPP is linked to type 2 diabetes mellitus.