Mechanism underlying oxidative stress-mediated lipotoxicity
In a nutshell, the researchers in this study found that elevated triglycerides (as would be found in insulin resistance) get sucked up into the macrophages (a type of white blood cells), and once there, started to destroy the mitochondria of the cell resulting in cell death. The death of a macrophage in the bloodstream can lead to the production of foam cells and subsequent plague in the arteries.
Interestingly, vit C, NAC and resveratrol protected the macrophages from this death. So, to extrapolate into a living, breathing human, antioxidants protect the cells that produce plaquing in the arteries, resulting in less plaque.