Insulin resistance--a risk factor for coronary heart disease?

Fasting insulin secretion was assessed by measuring fasting serum C-peptide levels in 529 women and 399 men aged 18-90 years, to study the relationship between insulin secretion, insulin resistance and risk factors for coronary heart disease. Subjects with low serum high density lipoprotein (HDL) cholesterol levels showed higher mean serum insulin and C-peptide levels than subjects with normal HDL cholesterol levels. In male subjects these differences were significant for both serum insulin and serum C-peptide results (P less than 0.005). In female subjects serum insulin results differed significantly (P less than 0.0005) but for the difference in mean serum C-peptide levels P was equal to 0.012. Fasting serum C-peptide correlated negatively with serum HDL cholesterol. However, serum C-peptide also correlated with serum triglyceride and serum triglyceride correlated negatively with serum HDL cholesterol. Each correlation was statistically significant (P less than 0.001). Multiple regression analysis suggested that the apparent association of C-peptide with HDL cholesterol was a consequence of the interrelated association between C-peptide, triglyceride and HDL cholesterol. The analysis was consistent with the hypothesis that obesity and increased insulin resistance were associated with increased insulin secretion and in turn with high serum triglyceride levels and consequentially low levels of serum HDL cholesterol. The data were compatible with the suggestion that insulin resistance rather than fasting insulin concentration per se could be a risk factor for coronary heart disease.