CTSB and Alzheimer disease: Alzheimer's disease shares many commons with T2DM, so that some scientists proposed to call Alzheimer’s disease "type 3 diabetes" or "diabetes of the brain." Calpain small subunit 1 (CAPNS1), a highly-conserved cysteine protease, which have been implicated in neurodegenerative processes after oxidative stress stimulation, is more active in GK.