Serum levels of C-peptide are associated with coronary artery calcification in patients with rheumatoid arthritis.

C-peptide has pro-atherogenic effects in animal models, and elevated C-peptide levels are associated with cardiovascular and all-cause mortality in patients undergoing coronary angiography. This cross-sectional study investigated the association between C-peptide serum levels and coronary artery calcification (CAC) in patients with rheumatoid arthritis (RA), a high-risk group for cardiovascular events. Fifty-four patients with RA were recruited from an arthritis outpatient department at the University Hospital in Aachen, Germany. CAC was measured by multi-slice CT scan, and blood samples were drawn from all patients for the analysis of C-peptide and other cardiovascular biomarkers. Mean serum levels of C-peptide (1.187 ± 0.771 vs 0.745 ± 0.481 nmol/L, p = 0.02), YKL-40, LDL cholesterol, and triglycerides were significantly higher in patients with CAC (n = 32, 59 %) compared to those without CAC (n = 22, 41 %). Univariate analysis revealed a significant association of C-peptide [OR 4.7, 95 % CI (1.1, 20.2)], YKL-40, triglycerides, hypertension, smoking, age, and male sex with the presence of CAC. After adjustment for body mass index, cholesterol, diabetes, adiponectin, calcium, and phosphate, C-peptide was still significantly associated with CAC in a multivariate logistic regression model. In conclusion, C-peptide serum levels are independently associated with the presence of CAC in patients with RA. These data suggest a potential role of C-peptide in cardiovascular disease in patients with RA.