Here, we aimed to investigate the mediating effects of lipid and insulin/glycaemic traits on the effect of BMI on CHD using a large MR study, including over 60,000 individuals with CHD, and to analyse a wider set of potential mediators including glycaemic traits (fasting glucose and insulin, HbA1c, type 2 diabetes) than previous studies. This evidence concerns the gene INS and type 2 diabetes mellitus.