Background: Diabetes mellitus (DM) is a risk factor for the development of the coronary heart disease (CHD), and individuals with DM have more extensive atherosclerosis, more cardiac events, and higher prevalence of silent ischemia as compared with individuals without DM. Objective: The aim of the study is to assess the association of significant coronary arterial disease, coronary calcification and carotid intima media thickness with glycosylated hemoglobin levels in patients without history of diabetes mellitus sent for coronary CT angiography. Patients and methods: This prospective study included 39 patients who underwent 320 Multi-slice CT coronary angiography (Aquilion ONE 320 MSCT) at (Nasr-City Police Hospital) through the period from May 2017 to April 2018. They divided into 3 equal groups according to HbA1c (G1, non-diabetic, G2, pre-diabetic and G3 diabetic). The study was approved by Ain Shams University academic and ethical committee and an informed written consent was obtained from all patients. Results: At level of multi-slice CT coronary, CCS was significantly higher in Group C than in Group A and B. But no significant difference could be picked in subgroup analysis between Group A and Group B. There were no significant differences among groups as regarding significant coronary artery stenosis. But there was a trend towards significance in Group C; however, it failed to reach significance mostly because of the small sample size. At level of carotid Doppler US, there were significant differences between groups as regarding bilateral CIMT. But this significance was mainly between Group C and the other groups in subgroup analysis. As regarding correlation, age and HbAlc had a positive strong correlation with CCS, LT CIMT, and RT CIMT. Conclusion: HbAlc positively correlates with coronary and carotid atherosclerosis and patients with mild elevation of HbAlc has significantly more CIMT than individuals with normal HbAlc.