Type 1 and type 2 diabetes both accelerate cardiovascular disease, yet the triggers are likely different for the two types of diabetes. Results from large-scale clinical trials suggest that intense blood glucose control can reduce cardiovascular events many years later in patients with type 1 diabetes. In type 2 diabetes, mechanisms related to insulin resistance and obesity may be more prominent in promoting atherosclerosis. In this article, we discuss the potential effects of hyperglycemia and diabetes-induced lipid abnormalities on atherosclerosis, particularly focusing on advanced stages of atherosclerosis and evidence from mouse models. In addition, we discuss new research findings in monocyte/macrophage biology that may present intriguing new areas of research related to diabetes and atherosclerosis.