Background Hyperglycemia on admission is a predictor of an unfavorable prognosis in patients with ST-elevation Acute Myocardial Infarction (AMI). Data concerning associations between an elevated glucose level on admission and other in-hospital complications are still limited. Methods A total of 1,137 AMI patients with complete admission blood glucose level (ABGL) analysis were identified and stratified according to ABGL. Results A total of 16.1% patients had admission glucose level <5 mmol/L, 36.1% <7 mmol/L, 20.2% <9 mmol/L, 9.9% <11 mmol/L and 17.7% >= 11 mmol/L. Compared with the euglycemia group, both the hypo- and hyperglycemia groups were associated with higher in-hospital mortality. In-hospital mortality of diabetic patients with hypoglycemia (12.2%) was higher than that of diabetic patients with either euglycemia or mild hyperglycemia (11.1%, or 10.7% relatively). The same results were seen in non-diabetic patients. In the logistic regression analysis, admission glucose and cardiac function of Killip grade were the independent predictors of in-hospital death for patients with AMI. Conclusion Elevated admission glucose levels are associated with an increased risk of life-threatening complications in diabetic and non-diabetic AMI patients. Compared with the euglycemia group, hypoglycemia was associated with a higher trend of in-hospital mortality.