Morphological evaluation using proximity ligation assay and Western blot analysis of IAPP and Aβ in islets of diabetics and cerebral Aβ deposits of AD cases revealed co-localization of IAPP and Aβ in brain and cerebrovascular amyloid deposits, while Aβ reactivity was not identified in any amyloid aggregates of endocrine pancreas. This evidence concerns the gene IAPP and Alzheimer disease.