C-Peptide and its career from innocent bystander to active player in diabetic atherogenesis.

The incidence and prevalence of diabetes are increasing worldwide. According to the International Diabetes Federation, more than 55 million people in the European region have diabetes, and this number is expected to rise to 64 million in 2030, with most of the cases being due to type 2 diabetes. Diabetes is associated with potentially serious microvascular and macrovascular complications such as nephropathy, neuropathy, and retinopathy as well as coronary artery disease. The pathophysiological mechanism behind this phenomenon is complex. In recent years the impact of proinsulin C-peptide in the development of vascular disease has been highlighted, but it displays differential function in type 1 and type 2 diabetes. In type 1 diabetes, which is characterized by a lack of insulin and C-peptide, supplementation of C-peptide has been shown to improve microvascular complications. In type 2 diabetes, however, C-peptide levels are increased above normal levels and correlate with the occurrence of macrovascular complications and cardiovascular deaths. This review focuses on the impact of C-peptide in the atherogenic process.