The results found that high circulating adiponectin was causally associated with reduced risk of type 2 diabetes (beta-estimate: −0.030, 95% CI: −0.048 to −0.011, SE: 0.009, P-value = 0.002) and may be the risk factor of coronary artery disease (beta-estimate: 0.012, 95% CI: 0.001 to 0.023, SE: 0.006, P-value = 0.030). This evidence concerns the gene ADIPOQ and type 2 diabetes mellitus.