High blood levels of the serum C-peptide are linked to heart disease and death in people without diabetes, according to a large study published in CMAJ (Canadian Medical Association Journal).

Researchers looked at data from the Third Nutrition and Health Examination Survey (NHANES III) and the NHANES III Linked Mortality File to determine the link between C-peptide levels and death from all causes as well as from heart disease. They looked at mortality data on 5902 adults aged 40 years or older representative of the US population. People with high serum C-peptide levels (higher than 1.018 nmol/L) had a 1.8- to 3.2-fold increased risk of death from all causes as well as cardiovascular disease–specific death compared with people with low C-peptide levels (lower than 0.440 nmol/L). The risk increased as C-peptide levels increased.

"We found a significant association between serum C-peptide levels and risk of all-cause, cardiovascular-related disease and coronary artery–related mortality among adults without diabetes," writes Dr. Kyoung-bok Min, Department of Occupational and Environmental Medicine, Ajou University School of Medicine, Suwon, Republic of Korea, with coauthor.

The study authors found that C-peptide levels were better at predicting mortality than other measures such as glycated hemoglobin and fasting blood glucose. Although the reason for the increased risk of death has not been determined, the authors suggest it may be because of the relationship between C-peptide levels and risk factors for atherogenic vascular issues.

"Our findings support the potential relevance of serum C-peptide as a predictor of adverse health outcomes and indicate that elevated C-peptide levels may be an important predictive marker of an increased risk of death," they conclude.