Assessment of the Association between Mean Hemoglobin A1c Levels for 5 Years and Coronary Artery Disease by Coronary Angiography in Nondiabetic Patients

Background: The effects of glucose on cardiovascular events or mortality in nondiabetic patients has been recently reported. However, since atherosclerosis can be formed over a long period of time, it is necessary to devote several years to unveil the relationship between the two factors. Here, we attempted to find out the relationship between the mean hemoglobin A1c (HbA1c) level and HbA1c variability for 5 years and coronary artery disease (CAD) by using coronary angiography (CAG) to assess nondiabetic patients. Methods: We reviewed patients who performed CAG who were followed up for at least 5 years after the initial diagnosis. The fasting blood test was performed annually for glucose and HbA1c level. CAD was defined as more than 50% of luminal narrowing. The severity of CAD was divided into two groups depending on whether no vessels were involved or one more vessel were involved (CAD(-) or CAD(+), respectively). Results: The patients in CAD(+) group had higher mean HbA1c level for 5 years than CAD(-) group (5.71 +/- 0.40 vs. 5.86 +/- 0.68; P = 0.04). Mean HbA1c was a significant predictor for CAD in multiple regression (odds ratio, 2.224; P = 0.028). The percentage of patients with CAD was significantly higher in patients with > 6.2% of mean HbA1c levels compared to patients with < 6.2% of mean HbA1c levels (P < 0.019). Conclusion: When the mean HbA1c levels were above 6.2%, the risk of CAD was higher. Also this study shows that HbA1c level can be one of the predictors for CAD even if the patients do not have diabetes.