The risk of dementia was doubled for current smokers (HR = 1.97; 95% CI = 0.53, 7.32) and for individuals with diabetes (HR = 2.18; 95% CI = 1.14, 4.17) and tripled for carriers of the APOE ε4 allele (HR = 3.11; 95% CI = 1.92, 5.05) (Table S4). This evidence concerns the gene APOE and diabetes mellitus.