Background: Admission hyperglycemia is a common finding in patients with acute myocardial infarction (AMI) and is associated with adverse outcomes. However, its prognostic significance in patients with and without diabetes remains unclear. Methods: This retrospective cohort study included 198 patients hospitalized with AMI. Patients were categorized based on diabetes status and the presence of admission hyperglycemia (blood glucose >180 mg/dL). Primary outcomes included mortality and major adverse cardiovascular events (MACE) within 12 months. Kaplan-Meier survival analysis and Cox proportional hazards modeling were used to assess the impact of hyperglycemia on outcomes. Results: Admission hyperglycemia was observed in 53% of patients. Mortality was significantly higher in hyperglycemic patients (22%) compared to normoglycemic patients (8%) (p < 0.05). MACE occurred in 40% of hyperglycemic patients versus 24% of normoglycemic patients (p < 0.05). Diabetic patients with hyperglycemia had the highest MACE incidence (45%). Cox regression analysis showed that admission hyperglycemia was an independent predictor of mortality (HR 2.4, 95% CI 1.3-4.5, p < 0.01). Conclusion: Admission hyperglycemia is a significant predictor of mortality and MACE in AMI patients, with a stronger impact in diabetics. Early glycemic management may improve outcomes.