OBJECTIVE-Dysglycemia is associated with poorer prognosis in patients with acute myocardial infarction (AMI). Whether admission glycemic variability (GV) has important value in prognosis of AMI patients is still unknown. The aim of the study is to investigate the prognostic value of admission GV, glucose, and glycosylated hemoglobin (HbA(1c)) in AMI patients. RESEARCH DESIGN AND METHODS-We measured blood glucose, HbA(1c), and GV on admission in 222 consecutive patients with diagnosed AMI. GV, indicated as the mean amplitude of glycemic excursions (MAGE), was determined by a continuous glucose monitoring system. MAGE was categorized as >= 3.9 or <3.9 mmol/L, admission glucose as >= 8.61 or <8.61 mmol/L, and HbA1c as >= 6.5 or <6.5%. Participants were followed up prospectively for 12 months. The relationship of admission MAGE, glucose, and HbA1c to the major adverse cardiac event (MACE) of AMI patients was analyzed. RESULTS-In 222 enrolled patients with AMI, the rate of MACE by MAGE category (<3.9 or >= 3.9 mmol/L) was 8.4 and 24.1%, respectively (P = 0.001), by admission glucose category (<8.61 or >= 8.61 mmol/L) was 10.1 and 21.6%, respectively (P = 0.020), and by HbA(1c) category (<6.5 vs. >= 6.5%) was 10.7 versus 18.7%, respectively (P = 0.091). In multivariate analysis, high MAGE level was significantly associated with incidence of MACE (hazard ratio 2.419 [95% CI 1.273-9.100]; P = 0.017) even after adjusting for Global Registry of Acute Coronary Events risk score, but admission glucose and HbA(1c) was not. CONCLUSIONS-Elevated admission GV appears more important than admission glucose and prior long-term abnormal glycometabolic status in predicting 1-year MACE in patients with AMI. Diabetes Care 36:1026-1032, 2013