Aim To study the relationship between plasma creatinine and the severity of coronary artery stenosis in patients with diabetes mellitus. Methods Ninty-one patients with diabetes mellitus underwent coronary angiograhy were evaluated with plasma creatinine before the procedures; in 55 patients with coronary heart disease (CHD), the relationships between plasma creatinine and the Leaman coronary artery score (LCAS) were assessed. Results The plasma creatinine of CHD group (114.0±28.6 μmol/L) was remarkably higher than that (80.5±25.2 μmol/L) in no-CHD group (p<0.01). In CHD group, the plasma creatinine had significantly positive correlation to Leaman coronary artery score (r=0.64, p<0.01), in the sub-group with hypertension (diabetes mellitus + hypertension), creatinine had Singificantly positive correlation to LCAS (r=0.81, p<0.01). Conclusion The plasma creatinine may be used to assess the severity of coronary artery stenosis in the patients with diabetes mellitus.