Background: We have previously shown that insulin is not a major risk factor for CHD. Our data have been re-analysed with longer follow-up and the homeostasis model assessment (HOMA) method.
Design: Prospective cohort study of 57- and 67-year-old men.
Methods: Insulin resistance was estimated with the HOMA equation. Standard methods were used to measure risk factors. The endpoint (CHD) was the combination of non-fatal myocardial infarction and fatal CHD during 13 years of follow-up.
Results: The risk of CHD increased 2.5-fold in known diabetics compared with those with normal glucose tolerance, 2.2-fold among those in the highest compared with the lowest quintile of insulin resistance, and 2.4-fold among those in the highest compared with the lowest quintile of fasting insulin. Increased physical activity decreased the risk of CHD by 65%. Cholesterol was also a significant risk factor for CHD but blood pressure, obesity and smoking were not related to the incidence of CHD.
Conclusion: Insulin resistance is a significant risk factor for CHD. Whether it is a causal risk factor remains to be proven. Regular physical activity protects against CHD.