APOE and type 2 diabetes mellitus: In the meta-analysis, four studies were included and provided a strong evidence for the APOE ε4 mutation elevating the risk of CAD in patients with T2DM (ε3/ε4+ε4/ε4 vs. ε3/ε3, OR = 1.51, 95% CI = 1.13–2.02).