IAPP and type 2 diabetes mellitus: The limitations of this study are: 1) this is a cross-sectional study, and we cannot conclude a protective relationship between a high concentration of amylin in plasma and attenuated cognitive decline; 2) this analysis does not include AD diagnosis, neuroimaging or autopsy measure, so the relationship between plasma amylin and brain structures or pathology is unknown; and 3) this study does not have hemoglobin A1C measurements which serve as a better biomarker to diagnose type 2 diabetes.