Background: Patients with diabetes mellitus (DM) experiencing non-ST elevation myocardial infarction (NSTEMI) have an increased risk for major adverse cardiac and cerebrovascular events (MACCE). This study aimed to explore the relationship among risk variables in NSTEMI patients with a history of Type 2 diabetes mellitus as well as those with newly diagnosed Type 2 diabetes mellitus concerning the incidence of MACCE. Methods: This retrospective cohort study utilized data from the Acute Coronary Syndrome Registry at Dr. Wahidin Sudirohusodo Hospital, Makassar, Indonesia, collected between January 2021 and December 2023. A total of 129 NSTEMI patients with diabetes were included and divided into two groups: those with a prior history of Type 2 DM (n=88) and those newly diagnosed with Type 2 DM at admission (n=41). The primary outcome was the occurrence of MACCE, which included all-cause mortality, recurrent myocardial infarction, stroke, and heart failure. Statistical analyses were conducted using logistic regression and Chi-square tests. Results: Patients with a prior diagnosis of diabetes had a significantly higher incidence of MACCE compared to those newly diagnosed (40.31% vs. 12.40%, OR 2.26, 95% CI: 1.064.82, p=0.034). The most significant risk factors associated with MACCE were reduced left ventricular ejection fraction (LVEF), lack of revascularization, and elevated hs-Troponin I levels. Heart failure was the most prevalent MACCE component in patients with a history of diabetes (OR 8.17, p=0.002), while stroke occurred only in this group but was not statistically significant. Elevated hs-Troponin I levels were correlated with MACCE only in patients with a prior diagnosis of diabetes, indicating more severe underlying coronary artery disease. Conclusion: NSTEMI patients with a prior history of Type 2 DM face a markedly higher risk of MACCE, particularly heart failure. Reduced LVEF, lack of revascularization, and elevated hs-Troponin I are significant predictors of adverse outcomes. These findings emphasize the need for rigorous risk factor control, timely revascularization, and vigilant cardiac function monitoring in diabetic NSTEMI patients. Further prospective research is warranted to refine risk stratification and management strategies for this high-risk population