Background: For coronary artery disease, lipoprotein (a), or Lp (a), is a well-established risk marker. Objectives: The aim of the current work was to determine the correlation between the severity of coronary artery disease and the serum lipoprotein (a) level in diabetic patients. Subjects and methods: At the National Heart Institute, Cairo, we conducted this cross-sectional observational study. From July 2021 to January 2022. 114 Type 2 diabetic individuals qualified for coronary angiography were enrolled in the study. All the participants in the trial were subjected to full history taking, clinical examination, ECG, Echocardiography, complete blood count, liver enzymes and serum creatinine, Lipoprotein (a) measurement and coronary angiography. Results: According to the results of our research, patients with high levels of lipoprotein (a) also had higher Syntax scores (p-value < 0.001). On the contrary, patients' lipoprotein (a) levels did not correlate statistically with any of the other measurements taken (p-value > 0.05). Conclusion: It could be concluded that patients with diabetes may have an increased risk of cardiovascular disease if their Lp (a) level is elevated, and the Lp (a) level is an essential clinical marker in both the general population and those with diabetes. A higher Lp (a) level in type 2 diabetics, according to our findings, is of great clinical significance.