Serum C-peptide as a key contributor to lipid-related residual cardiovascular risk in the elderly.

OBJECTIVES: The serum levels of C-peptide, an important risk factor for cardiovascular disease (CVD), increase with age. This study aimed to investigate the association between serum C-peptide and increased risk for CVD with altered lipid metabolism in the elderly.

METHODS: This was a population-based cross-sectional study that included 3091 elderly participants aged ≥65 years. Serum C-peptide and lipid levels were measured according to standard protocols. Sampling weights were used to estimate the characteristics of study participants. Stratified analysis of covariance was used to evaluate the changes in the serum lipid levels according to quartiles of serum C-peptide levels, and the linear trend was assessed using a linear model. The logistic regression model was carried out to determine the association between the serum C-peptide levels and serum lipid levels.

RESULTS: The results of the analysis of covariance stratified by sex and serum insulin level showed that the serum triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels were significantly associated with changes in the serum C-peptide levels, independent of the serum insulin level. The logistic regression analyses indicated that the serum C-peptide levels were positively associated with the serum TG levels, and negatively associated with the serum HDL-C levels. A significant dose-response association was obtained in both men and women.

CONCLUSIONS: Serum C-peptide levels were strongly associated with increased serum TG and reduced HDL-C levels in the elderly. Our results suggest that serum C-peptide increases the risk of CVD via a pathway that increases TG or decreases HDL-C levels.