ABSTRACT Introduction: Patients with Non ST elevation myocardial infarction , the incidence of heart failure was twice in diabetic versus non diabetic ones .There is positive correlation between diabetes mellitus duration and the risk of developing acute coronary syndromes , An independent relation between the duration of diabetes mellitus and critically and fatal coronary artery disease has been shown in men . Some studies suggest that coronary artery disease and HbA1c level are predictors of cardiovascular morbidity and mortality . Aim of the study: To study the interventional outcomes of high-risk non-ST elevation acute myocardial in diabetic and non-diabetic patients. Patients and methods: Prospective study was conducted in, Zagazig University Hospitals , it included 480 patients , diagnosed by ECG, cardiac biomarker and Grace Score 6 as high risk NSTE-ACS , divided into (272 Diabetic and 208 Non-diabetic). Patients were classified according to GRACE score into 3 categories high (>140), intermediate (70–140), and low (1-70), the patients underwent early emergency, or elective coronary angiography within 3 days of admission. After intervention (PCI) , followed up for 48 hours to detect complications and death. Results: There was no significant difference between the two groups as regard age and hypertension . Gensini and Grace scores were significantly higher in diabetes. In patients of high Gensini and syntax scores only diabetes was an independent predictor of the extent and severity of coronary artery obstruction. Conclusion: Diabetes Mellitus has a significant correlation with angiographic complexity and interventional outcome in patients with Non-ST elevation myocardial infarction. Key words: Diabetes Mellitus, Non-ST elevation myocardial infarction. " Effects of Diabetes Mellitus on Interventional Outcome in Patients with Non-ST- Myocardial Infarction"