APOE and diabetes mellitus: For all participants, plasma ET levels were lower in male participants and APOE ε4 carriers (p < 0.001 and p = 0.004, respectively, Mann–Whitney U tests) and were negatively associated with age (Spearman’s r = −0.18, p < 0.001), hypertension, diabetes, and cardiovascular disease (p = 0.006, p = 0.030 and p = 0.001, respectively, Mann–Whitney U tests), but positively associated with the education level (Spearman’s r = 0.20, p < 0.001), but not with BMI or hyperlipidemia (both p > 0.1).