Background: One of the most undesired complications after open heart operations is bleeding. In our study, we set ourselves two different goals: examining ‘Papworth, Will-Bleed, Track and Trust’ bleeding scoring systems to determine the most predictive one among diabetic patients undergoing isolated coronary bypass surgery, and determining the variables that should be included in the new scoring systems to be established for this patient group. Methods: The files of 297 diabetic patients who underwent isolated coronary artery bypass operation between 2017-2019 were retrospectively reviewed. Patients who underwent emergency surgery with a beating heart, those with reoperated open hart surgery, those with ticagrelor use, and those who died within the first 24 postoperative hours were excluded from the study. Drainage from the thorax and mediastinal tubes and blood product transfusions to the patients within the first 24 hours were noted and analyzed according to scoring systems. Results: Scoring systems are evaluated based on ‘European Multicenter Study on Coronary Artery Bypass Grafting Bleeding Severity (E-CABG)’. In this study including diabetic patients only, Papworth was better predictive of E-CABG bleeding Grade 2-3. We found that Will-Bleed, Track, Trust, the other scoring systems we examined had discriminatory value in terms of E-CABG bleeding Grade 2-3 in our study group. Among the parameters in the scoring systems, we concluded that gender, preoperative hemoglobin (or hematocrit) value, preoperative platelet count, use of antiplatelets until less than five days prior to the operation, and preoperative creatinine (or eGFR) values should be included in the scoring system we aim to establish in the future, called the “Optimum Risk Score for Bleeding (ORS).” Conclusion: Considering the possible risks of bleeding and blood product transfusion, scoring systems that will provide accurate results for patient blood management will be lifesaving and increase the cost-effectiveness of the treatment.