Insulin Resistance and Fasting Hyperinsulinemia Are Risk Factors for New Cardiovascular Events in Patients with Prior Coronary Artery Disease and Normal Glucose Tolerance

Background: Insulin resistance and hyperinsulinemia are important risk factors for coronary artery disease (CAD) and cardiovascular event (CVE). However, their independent relationship to new CVE in patients with normal glucose tolerance (NGT) and CAD is not known. Methods and Results: Subjects of this 3-year observational study were 102 patients with CAD. Plasma glucose and insulin concentrations were determined at 2 time points (baseline and post oral glucose tolerance test [OGTT]. The fasting plasma glucose <110mg/dl and post-OGTT<140mg/dl was diagnosed as NGT (World Health Organization criteria). Insulin resistance was evaluated by the homeostasis model assessment of insulin resistance (HOMA-IR). Of the 102 patients, 23 had onset of new CVE, including 19 with new CAD. They had significantly higher fasting and post-OGTT insulin levels and HOMA-IR than those without new CVE (P<0.01, 0.031 and <0.01, respectively). Using the univariate Cox proportional hazards model, fasting and post-OGTT insulin values, HOMA-IR and high density lipoprotein (HDL) cholesterol differed significantly between the 2 groups. The multivariate Cox model showed that the effect of fasting plasma insulin and HOMA-IR remained significant and independent of HDL cholesterol. Conclusion: Fasting hyperinsulinemia and high insulin resistance increased the risk of new CVE in patients with NGT and CAD.