Fasting Hyperinsulinemia Among Nondiabetics: Independent Association with Coronary Disease

Controversy is not resolved whether plasma insulin levels serve as a risk indicator for coronary risk in the general population. The purpose of this cross-sectional study was to evaluate the role of insulin concentrations with respect to prevalent coronary heart disease (CHD) in the Turkish population sample. In 761 men and women (>30 years of age) residing in two large regions of the Turkish Adult Risk Factor Survey in 2001 plasma insulin levels, in addition to other risk parameters, were assessed. Diagnosis of CHD was based on clinical findings and Minnesota coding of resting ECGs. The chemiluminescent immunometric method was used to determine insulin values. Fasting log insulin concentrations in 688 nondiabetic persons averaged 9 in men and 8.8 mlU/L in women (p>0.05); they increased modestly with age. Best determinants of fasting insulin on multivariate analysis were waist circumference (and body mass index). In addition, triglycerides, blood pressure and, inversely, HDL-cholesterol values displayed strong correlations with insulin. In a logistic regression model controlling for age and obesity, the odds ratio (OR) for CHD in the quartle with hyperinsulinemia (?10 mU/L) as opposed to the lowest quartile was 2-fold in both genders (p<0.05). Adjustment for dyslipidemia, blood pressure, glucose intolerance, physical activity and smoking status did not attenuate the OR, nor did adding C-reactive protein into the model (which was correlated with fasting insulin only in women). Thus, hyperinsulinemia may not only add useful information on CHD likelihood to that provided by the other risk factors, it may also contribute to the coronary risk independent of the latter factors.