Role of fasting serum C-peptide as a predictor of cardiovascular risk associated with the metabolic X-syndrome

Insulin resistance with increased insulin and C-peptide levels is the basis of the metabolic X-syndrome, so it is reasonable to expect them to be a good predictor of associated cardiovascular risk factors. A total of 29 patients (21 postmenopausal women and 8 men) with type 2 diabetes mellitus (mean duration 14.6 years, 95% CI 11.9 to 17.3 years), all older than 50, were studied for possible links between fasting serum C-peptide levels and other vascular risk factors. The mean value of the C-peptide in the group was 0.627 nmol/l (95% CI: 0.464 to 0.789 nmol/l). We found statistically significant correlations between C-peptide and triacylglycerols (TG; r=0.474; p=0.009), HDL-cholesterol (inverse; r = -0.567; p = 0.001) and various lipoprotein ratios: atherogenic index (= total/HDL cholesterol: r = 0.599; p = 0.0006) or TG/HDL (r = 0.587; p = 0.0008). C-peptide also correlated with the body mass index (BMI: r = 0.519; p= 0.004) and leptin (r = 0.492; p = 0.007). After the coefficient CpG (C-peptide x fasting glycemia) was introduced, the correlations with lipoproteins became even stronger. We suggest that elevated (fasting) serum C-peptide levels constitute a clinically important marker of the cardiovascular risks associated with the metabolic X-syndrome. It can be used as an effective tool for the early detection of diabetic patients at particular risk for atherosclerotic cardiovascular diseases and needing early preventive measures or aggressive treatment.