Abstract: Objective  To investigate the correlation between the severity of acute coronary syndrome(ACS) and red blood cell distribution width(RDW) of type 2 diabetes mellitus(DM) and non-diabetic patients.
  Methods  The 497 ACS patients were selected and divided into the 2-DM group(group 1) and the non-diabetic group(group 2), performed coronary angiography(CAG) separately. According to SYNTAX score, group 1 and group 2 were divided into three groups: low group, middle group and high group(group 1：A1, B1, C1； group 2：A2, B2, C2), measuring the RDW width of each group, and conducting comparison and correlation analysis. Glycated hemoglobin(GHb) levels between groups A1, B1 and C1 were measured, and intra-group comparison and correlation analysis were performed.
  Results  The RDW level of A1, B1, C1 in group 1 and A2, B2 and C2 in group 2 was progressively increased with statistically significant difference(P＜0.05), and the RDW level was positively correlated with SYNTAX score(r=0.675, P＜0.01). The RDW level of all 497 patients was positively correlated with SYNTAX score(r=0.686， P=0.041). There was no statistically significant difference in the correlation coefficient between RDW level and SYNTAX score（Z=-1.960， P=0.373）between groups 1 and 2.
  Conclusion  The width of the red blood cells was not affected by the blood glucose level. Whatever type 2 diabetes mellitus and non-diabetic patients, RDW can be used as the evaluation index of the severity of ACS coronary blood vessels.

Key words: acute coronary syndrome, diabetes mellitus, type 2, red blood cell distribution width