LEP and type 2 diabetes mellitus: The association of AN with metabolic traits and abnormalities has been fairly well established, including with insulin resistance (rg = −0.29), fasting insulin (rg = −0.24), leptin (rg = −0.26) and type 2 diabetes (rg = −0.22), and a positive genetic correlation with HDL cholesterol (rg = 0.21) (Adams, Reay, Geaghan, & Cairns, 2021; Ilyas et al., 2019; Watson et al., 2019).