The influence of admission hyperglycemia and diabetes on short- and long-term mortality of patients with acute myocardial infarction (AMI) in the percutaneous coronary intervention (PCI) era was investigated. From 1996 to 2003, a total of 802 consecutive patients with AMI underwent coronary angiography. Primary PCI was performed in 724 patients (90%). Three-year mortality curves were constructed using the Kaplan-Meier method. Cox proportional hazard regression was used to identify independent predictors of 30-day mortality and mortality from 30 days to 3 years. There were 261 patients with admission hyperglycemia (admission glucose>or=11.1 mmol/L) and 212 patients with diabetes. Admission hyperglycemia was associated with a significantly higher 30-day mortality rate (8.4% vs 2.4%, p<0.001). However, there was no significant difference in 30-day mortality rates between diabetic and nondiabetic patients (5.7% vs 3.9%, p=0.29). Conversely, diabetes significantly increased mortality from 30 days to 3 years (10.0% vs 5.5%, p=0.03), but admission hyperglycemia did not (8.4% vs 5.9%, p=0.19). Multivariate analysis showed that hyperglycemia was an independent predictor of 30-day mortality (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.13 to 2.61, p=0.01), but diabetes was not (OR 0.84, 95% CI 0.55 to 1.27, p=0.42). Diabetes was independently associated with mortality from 30 days to 3 years (OR 1.43, 95% CI 1.02 to 1.97, p=0.04), but hyperglycemia had a neutral effect (OR 0.98, 95% CI 0.70 to 1.36, p=0.92). In conclusion, in the PCI era, admission hyperglycemia was associated with short-term mortality, whereas diabetes increased long-term mortality after convalescence in patients with AMI. Admission hyperglycemia and diabetes should be treated as 2 distinct disease states.