The Role of Insulin Resistance as a Risk Factor of Coronary Artery Disease

Jung, Sung Ae; Park, Si Hoon; Shin, Gil Ja; Lee, Woo Hyung

Abstract

BACKGROUND
Established risk factors for coronary artery disease include smoking, hypertension, diabetes mellitus and hypercholesterolemia. However, these account for less than 50% of the actual incidence of coronary artery disease and the importance of other risk factors is being increasingly realized. It has been known that insulin resistance associated with hyperinsulinemia is a pivotal link to several risk factors of coronary artery disease, including hypertension, glucose intolerance, dyslipidemia and obesity. Recently both experimental and clinical studies have produced evidence suggesting that high plasma insulin level may promote the development of atherosclerotic vascular diseasa. Several prospective studies showed independently that high plasma insulin is associated with an increased risk of major coronary artery disease. In our study, plasma glucose, insulin and C-peptide level were determined with oral glucose tolerance test to assess the insulin resistance or hyperinsulinemia as a risk factory of coronary artery disease. METHOD: From September 1993 to April 1995, after excluding patients with hypertension, diabetes mellitus, hypercholesterolemia and obesity, 17 patients with significant coronary artery stenosis and 10 control subjects with normal coronary finding were selected among the 226 patients who undertook coronary angiography. In the 17 cases(M:F=15:2) of coronary artery disease group, the mean age was 54+/-10 years, and in the 10 cases(M:F=8:2) of control group, 51+/-9 years. All were matched for age, gender and body mass index. Blood pressure, lipid and lipoprotein were measured and smoking history was assessed. Glucose, insulin and C-peptide responses to oral glucose tolerance test were also determined. RESULT: 1) There was no significant difference in systolic and diastolic and diastolic blood pressure, total-cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, ApoA and smoking history except ApoB between the subjects with coronary artery disease and normal control subjects. 2) In oral glucose tolerance test, the plasma glucose levels were not significantly different in the two groups. plasma insulin and C-peptide levels at 60 and 120 minutes were higher in the patient group than control, but the results lack statistical significance. The area under the insulin curve and C-peptide curve were larger in patient group than control, but the result lack statistical significance also.
CONCLUSION
Although our study dose not prove the hypothesis that insulin resistance or hyperinsulinemia is statistically an independent risk factor for coronary artery disease, this study showed the tendency of insulinresistance to be correlated with development of coronary artery disease. As this study has limitations due to small sample size, further study is required to confirm the role of hyperinsulinemia using a larger sample size.