INS and Alzheimer disease: Further, in a prospective study with the Rotterdam cohort, nondemented participants (6370 subjects) were followed up for 2.1 years, and the results demonstrated that DM doubled the risk of dementia (relative risk 1.9) and AD (relative risk 1.9); again, insulin-treated subjects were at highest risk of dementia (relative risk 4.3), concluding that DM contributes to the development of all dementia [97].