IAPP and diabetes mellitus: In vitro and in vivo studies show that islet amyloid polypeptide (IAPP; also known as amylin)23 can potentiate Aβ aggregation by colocalising in brain parenchyma.24 The increased peripheral inflammation in diabetics causes greater BBB permeability, which allows peripheral IAPP to enter the brain to further propagate the Aβ aggregation.