Serum bile acid levels vary in individuals, and increased fasting bile acids and serum C4 are correlated with type 2 diabetes (T2D) and ACVD.[84] Disruption of RCT contributes directly to the accumulation of oxidized LDL and fatty foam cells in the endothelium of the aortic wall and to the pathogenesis of atherosclerosis. Here, C4A is linked to type 2 diabetes mellitus.