In this study composed of approximately 20,000 European American and 6,200 African American participants, we identified three new loci associated with multiple metabolic trait domains: APOC1, BRAP, and PLCG1. These loci were in or near genes previously associated with atherogenic dyslipidemia, vascular inflammation, type I diabetes, vascular dysfunction, and central adiposity. This evidence concerns the gene PLCG1 and type 1 diabetes mellitus.