Background: Hyperglycemia, insulin resistance, and hyperinsulinemia represent important pathophysiological components of the prediabetic stage that result in arteriosclerosis and increased arterial stiffness. We sought to compare the aortic distensibility (AD) assessed by cardiac magnetic resonance (CMR) in prediabetic patients presenting with chronic coronary artery disease (CCAD) versus patients with normal HbA1C. Ninety-eight patients with CCAD were recruited. All patients were screened for HbA1C levels and then underwent a CMR study to assess AD of the aortic root and the ascending and descending thoracic aorta. Patients were classified into two groups: 52 prediabetic (HbA1C 5.7-6.4%) (study group) and 46 with normal glycemic status (HbA1C < 5.7%) (control group). Results: AD values at the aortic root (AR) (13.93 ± 5.17 vs 34.3 ± 9.65 Kpa-1 × 10-3), ascending aorta (AA) (13.17 ± 4.81 vs 28.1 ± 8.33 Kpa-1 × 10-3), and descending thoracic aorta (DA) (18.12 ± 4.34 vs 33.68 ± 7.57 Kpa-1 × 10-3) were significantly lower in the study group than in the control group (P value for all was < 0.001). Twenty-eight patients fulfilled the criteria for metabolic syndrome, and in those patients, AD was significantly lower than in those without metabolic syndrome. Aortic distensibility at the AR, AA, and DA had strong significant negative correlations with the level of glycosylated hemoglobin (AA, AR, DA; r − 0.66, − 0.68, − 0.58, respectively) (P < 0.001). Conclusion: AD values at different points (AR, AA, and DA) were significantly lower in prediabetic and metabolic syndrome patients than in controls. These values also showed a significant negative correlation with the levels of HBA1C.