Blood C‐peptide concentration as a proxy marker of cardiovascular disease: An observational cross‐sectional study

BACKGROUND AND AIMS: Cardiovascular diseases (CVDs) are among the leading causes of disability and early death in sub‐Saharan Africa. Most of the current blood tests for CVD diagnosis involve performing about three test profiles; often at additional cost to patients. C‐peptide, a cleavage product of proinsulin, is a promising marker that has the potential to serve as a proxy marker for diagnosing CVDs in resource‐poor settings. METHODOLOGY: The study was an observational cross‐sectional one and involved 127 consenting persons diagnosed with CVD and 127 individuals without CVD. The socio‐demographic and clinical characteristics of participants were obtained. Blood levels of C‐peptide, fasting plasma glucose (FPG), total creatinine kinase (CK), creatine kinase myocardial bound (CKMB), lactate dehydrogenase (LDH), propeptide of brain natriuretic peptide (PBNP), Troponin T, lipids, and biomarkers of kidney and liver function were analyzed using ELISA and an automated analyzer. Insulin resistance was computed using the modified homeostatic model assessment (HOMA‐IR). RESULTS: The CVD Group had significantly higher levels of C‐peptide, CK, CKMB, troponin T, PBNP, FPG, HOMA‐IR, and several selected kidney, liver, and lipid parameters compared to the non‐CVD Group (p < 0.05 for all). Troponin T recorded a positive correlation (r = 0.34, p < 0.001) with C‐peptide among the CVD Group. The sensitivity and specificity of C‐peptide in identifying CVD were 96.1% and 91.3% respectively (area under the curve = 0.938, p < 0.001). CONCLUSION: C‐peptide levels were higher in the CVD Group and appeared to be a valuable (high sensitivity and specificity) biomarker in detecting CVD.