Objective To investigate the characteristics of coronary's pathological changes in patients with impaired glucose tolerance. Methods Four-hundred and ninety patients who were suspected with ischemic chest pain were divided into three groups according to their OGTT results: (1) IGT group: n = 161,(2) 12DM group:n = 159, (3) NGT group: n = 170. Serum levels of triglyceride (TG) , total cholesterol (TC) , highdensity lipoprotein cholesterol (HDL-C) , low-density lipoprotein cholesterol (LDL-C) and high sensitive Creactive protein (hs-CRP) were detected, their body mass indexes (BMI) were calculated. General clinical information (including gender, age, history of smoking, history of hypertension) were collected. All the CAG results were analyzed and Gensini scores were assessed as well. Results The TG levels in the T2DM group and IGT group ([2. 41 ± 1.70] mmol/L and [2. 26 ± 1. 20] mmol/L) were significantly higher than that of the NGT group (1.95 ± 1.14) mmol/L, the differences were significant (t=0.4610,0.3124, P<0. 01 and 0.05,respectively),whereas there was no significant difference between the IGT group and T2DM group (P >0.05);No significant difference was found among the three groups about TC, HDL-C, LDL-C levels (either P > 0.05). The levels of hs-CRP in T2DM group ([2. 38 ± 1. 76] mg/L and IGT group [2. 33 ± 2. 03] mg/L) were higher compared with the NGT group ([1. 54 ± 1. 32] mg/L), the differences were significant (t = 0. 8391,0. 7815, Ps < 0. 01), whereas there was no significant difference between the IGT group and T2 DM group (P >0.05). BMIs of the IGT group ([25.50 ± 3.04]kg/m2) and T2DM group ([26.09 ± 2.86]kg/m2) were higher than that of the NGT group ([24. 70 ± 3. 27] kg/m2), the differences were significant (t = 0. 8063,1. 3947, P<0. 05 and <0.01, respectively),whereas no significant difference was found between the T2DM group and IGT group (P > 0. 05). The incidence of single coronary pathological changes was 44.7% in the NGT group,it was higher than that of the IGT group (23. 6%) and T2DM group (18. 9%) (x2 = 16. 310,25. 116,Ps < 0. 05), whereas there was no significant difference between the IGT group' and T2DM group (P > 0. 05);The incidences of 2 branches pathological changes in the T2DM group (37. 1%) and IGT group (39. 8%) were higher compared with NGT group (23. 5%) ,the differences were significant (x2 =1. 200,10. 099,Ps <0. 05),whereas there was no significant difference between the IGT group and T2DM group (P >0. 05) ;The incidences of 3 vessels pathological changes in the T2DM group (40.9%) and IGT group (33. 5%) were higher than that of the NGT group (20. 0%) , the differences were significant (x2 = 7. 767,17. 028, Ps < 0.05), there was no significant difference between the IGT group and T2DM group (P > 0. 05). The incidence of subtotal or total occlusion of the T2DM group and IGT group were 22. 6% and 18.0% respectively,both were higher than that of the NGT group(7. 6%) (x2 = 14. 573,8. 019 ,Pa < 0.05) , whereas no significant difference was found between the T2DM group and IGT group (P > 0. 05). The incidences of vascular diffusing pathological change in the IGT group (24. 8%) and T2DM group (30. 8%) were higher compared with the NGT group (12.4%) (x2 =8.583,16.724, Ps < 0.05), whereas there was no significant difference between the IGT group and T2DM group (P >0.05). The Gensini scores in the IGT group (55. 05 ± 22. 99) and T2DM group(56. 15 ± 24. 87) were significnatly higher than that of the NGT group (38. 03 ± 17. 38), the differences were significant ((t =17.0142,18. 1186,Ps <0.01),whereas there was no significant difference between the IGT group and T2DM group (P>0.05). Conclusion The incidences of 2 and 3 vessels pathological changes increase significantly in patients with IGT. Moreover, the incidences of occlusion and diffuse stenosis increase significantly. This is similar to the coronary artery pathological charactersitics in patients with diabetes, which indicates that IGT is closely related to the pathological severity of coronary artery. We should pay much attention to those patients with IGT in the clinical work.