Unrecognized glycometabolic disturbance as measured by hemoglobin A1c is associated with a poor outcome after acute myocardial infarction

Background Glycated hemoglobin A(1c) (HbA(1c)) is a measure of the average blood glucose levels over 2 months and is minimally affected by acute hyperglycemia often observed in myocardial infarction (MI). In a large population of high-risk patients with MI, we examined the prognostic impact of HbA(1c) in patients with and without a history of diabetes. Methods In the OPTIMAAL trial, patients with MI complicated with heart failure were randomized to losartan or captopril. Of the 2841 patients who had HbA(1c) measured at randomization, 495 (17%) reported a history of diabetes. The OF remaining patients without diabetes history were stratified into 3 categories according to HbA(1c) level: HbA(1c), < 4.9% (n = 1642); HbA(1c), 4.9% to 5.1 % (n = 432); and HbA(1c), > 5.1 % (n = 272). Mean follow-up time was 2.5 years. Results Mortality rate during follow-up was 18% in patients with a history of diabetes. Increasing HbA(1c) levels were associated with higher mortality rate among patients without diabetes history (13% in patients with HbA(1c) < 4.9%, 17% in patients with HbAjc 4.9%-5.1%, 22% in patients with HbAjc > 5.1%). Among patients with no prior history of diabetes, a 1% absolute increase in HbA(1c) level at baseline resulted in a 24% increase in mortality, whereas the level of HbA(1c) had no impact on mortality among the patients with well-known diabetes (multivariate analyses). Conclusions In this high-risk MI population, HbAjc level was a potent predictor of mortality in patients without previously known diabetes.