Background: Glycated hemoglobin (HbA1c) is a reliable marker of long-term glycemic control and has been increasingly linked to cardiovascular risk. Its association with angiographic severity of coronary artery disease (CAD) remains clinically significant. Aim: To evaluate the correlation between HbA1c levels and severity of CAD using the SYNTAX score in patients undergoing coronary angiography. Materials and Methods: A cross-sectional study was conducted on 120 patients undergoing coronary angiography. Patients were categorized into three groups based on HbA1c levels: Group A (7.5%). CAD severity was quantified using the SYNTAX score. Statistical analysis included ANOVA, Pearson correlation, and chi-square test. Results: Mean SYNTAX scores increased significantly across HbA1c groups: Group A = 12.4 ± 5.8, Group B = 19.8 ± 6.5, and Group C = 28.6 ± 7.2 (p < 0.001). Triple-vessel disease was more common in higher HbA1c groups (28%, 52%, and 78% respectively). HbA1c demonstrated a strong positive correlation with SYNTAX score (r = 0.71, p < 0.001). Conclusion: Rising HbA1c levels are associated with greater severity and complexity of CAD. HbA1c may serve as an effective adjunct marker for predicting CAD burden and improving risk stratification in clinical practice