Background: Coronary artery disease is one of the main causes of death in diabetes mellitus (DM). Egypt was listed among the world top 10 countries regarding the number of diabetic patients by the International Diabetes Federation (IDF). Aim of work: Assessment of the extent of coronary atherosclerotic disease and lesion tissue characterization among diabetic compared to non-diabetic Egyptian patients. Methodology: IVUS studies of 272 coronary lesions in 116 patients presented with unstable angina were examined. The patients were divided into two groups: diabetic group (50 patients with 117 lesions) and non-diabetic group (66 patients with 155 lesions). Results: As compared to the non-diabetic group, the diabetic patients were more dyslipidemic (84% vs 39.4%, p = 0.001) with higher total cholesterol level (194.6 +/- 35.3 vs 174.4 +/- 28.5 mg/ dl, p = 0.001) and higher LDL-C (145.3 +/- 27.1 vs 123.2 +/- 31.4, p = 0.001). Regarding lesions characteristics, the diabetic group had longer lesions (19.4 +/- 7.4 vs 16.3 +/- 7.9 mm, p = 0.002) with higher plaque burden (60.8 +/- 15.3 vs 54.8 +/- 14.0, p 0.002) and more area stenosis percentage (60.8 +/- 15.6 vs 55.6 +/- 14.1, p = 0.008). Structurally, the diabetic group lesions had more lipid content (19.8 +/- 8.8 vs 16.8 +/- 8.7, p = 0.008) and more necrotic core (17.6 +/- 7.4 vs 14.7 +/- 4.8, p = 0.008) but less calcification (6.9 +/- 3.6 vs 11.8 +/- 6.3, p = 0.001). The RI was negative in both groups, 0.95 +/- 0.13 in the diabetic group vs 0.98 +/- 0.19 in non-diabetic group (p = 0.5). Within the diabetic group lesions, the dyslipidaemic subgroup had more lipid content (23. +/- 5.2 vs 14.6 +/- 8.6, p = 0.01) but less fibrotic component (48.6 +/- 4.7 vs 59.1 +/- 13.6%, p = 0.01) and less calcification (10.9 +/- 6.8% vs 14.07 +/- 3.8%, p = 0.02) as compared to the nondyslipidaemic subgroup. Conclusions: Diabetic patients with coronary atherosclerosis in Egypt have longer lesions with higher plaque burden and more percent area stenosis with negative remodeling index. The diabetic lesions had more lipid content and more necrotic core but less calcification. (C) 2018 Egyptian Society of Cardiology. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.