Objective: C-peptide is a proinsulin cleavage product released from the pancreas in amounts equimolar to insulin, and elevated levels of C-peptide have been found in patients with insulin resistance and early type 2 diabetes mellitus. Recent data suggest that C-peptide could play a causal role in the pathophysiology of vascular disease, but nothing is known about the prognostic value of C-peptide concentrations in the circulation.
Research design and methods: We examined whether C-peptide is associated with cardiovascular and total mortality in 2,306 patients from the Ludwigshafen Risk and Cardiovascular Health Study who underwent coronary angiography at baseline (1997-2000).
Results: During a mean follow-up of 7.6 years, 440 deaths (19.1%) occurred, 252 (10.9%) of which were due to cardiovascular causes. Age- and sex-adjusted hazard ratios (HRs) in the third compared with the first tertile of C-peptide were 1.46 (95% CI 1.15-1.85; P = 0.002) for all cause and 1.58 (1.15-2.18; P = 0.005) for cardiovascular mortality. After further adjustment for common risk factors as well as markers of glucose metabolism, these HRs remained significant at 1.46 (1.10-1.93; P = 0.008) and 1.55 (1.07-2.24; P = 0.022), respectively. Moreover, patients in higher tertiles of C-peptide exhibited higher levels of markers of endothelial dysfunction and atherosclerosis as well as a more severe extent of coronary lesions.
Conclusions: In patients undergoing coronary angiography, C-peptide levels are independently associated with all cause and cardiovascular mortality as well as presence and severity of coronary artery disease. Further studies are needed to examine a potential causal role of C-peptide in atherogenesis in humans.