Objective: To compare hospital outcomes of acute myocardial infarction (AMI) in patients with andwithout diabetes mellitus.Methodology: This observational cohort study was carried out in the department of Cardiology,Postgraduate Medical Institute Govt. Lady Reading Hospital Peshawar. A total of 444 patients with AMIwere studied from December 2009 to December 2011. Among these half of patients were diabetic whilerests were non-diabetic. After enrolment in the study, patients were monitored for in- hospital complicationsofAMI.Results: Most of the baseline characteristics were similar between the two groups of patients. Howeverpatients in diabetic group had more hypertension, dyslipidemia, high glucose level, less smoking, high heartrate and raised blood pressure on presentation as compared to patients in non-diabetic group. Complicationrates were significantly higher in the diabetic group as compared to non-diabetic group. Complication ratesbetween diabetic and non-diabetic groups were atrial fibrillation (AF) 14.4% V 8.1%; P=0.036 respectivelywhile ventricular tachycardia (VT) 10.8% V 13.1% ;P=0.464, ventricular fibrillation (VF) 3.2% V 4.1 %;P=0.611, advanced AV blocks 12.2%V 6.3% ;P=0.033, acute heart failure (AHF) 24.8% V 17.1% ;P=0.047,cardiogenic shock(CS) 18% V 7.2%;P=0.001, recurrent MI (Re-MI) 14.4% V 7.7%; P=0.000, acute renalfailure 9%V5%; P=0.001 and death rate 13.5 % V 8.1 %; P=0.000 respectively.Conclusion: Diabetes mellitus is associated with an increase risk of in-hospital complications afterAMI.Key words: Diabetes mellitus, hospital Outcomes,Acute Myocardial Infarction