Aim To investigate the correlation of dimethyl arginine dimethylamine hydrolase 2（DDAH2） gene －449G/C polymorphism and plasma asymmetric dimethylarginine （ADMA） levels with atherosclerosis in type 2 diabetes （T2DM）. Methods The DDAH2 gene －449G/C polymorphism was detected by polymerase chain reaction-restricted fragment length polymorphism （PCR-RFLP） in 146 normal controls and 238 patients with type 2 diabetes （including 80 without atherosclerosis patients （D0 group）,71 early atherosclerosis patients （D1 group）,87 middle-late atherosclerosis patients （D2 group））. The plasma levels of ADMA were detected by enzyme linked immunosorbent assay （ELISA）. The genotype frequencies,allele frequencies and clinical index were compared among these groups. Results The G/G genotype frequencies and G allele frequencies in D1＋D2 group were significantly higher than those in D0 group （P<0.05）. In patients with type 2 diabetes,plasma ADMA level in G/G genotype group was significantly higher than that in C/C＋G/C genotype （P<0.05）. The ADMA levels among groups: D1＋D2 group＞D0 group,D2 group＞D1 group＞D0 group. A statistically significant difference was revealed after performing covariance analysis on the data （P<0.01）.Logistic regression analysis showed that plasma ADMA levels were the determinants of the occurrence and development of atherosclerosis. The G/G genotypes of DDAH2 gene were the determinants in atherosclerosis patients. Conclusions The G/G genotype of DDAH2 gene may be genetic predisposing factor of atherosclerosis in patients with type 2 diabetes in the Han population of Yunnan. The G/G genotype of DDAH2 gene carries higher ADMA levels. The level of plasma ADMA may be a predictor of the occurrence and development of atherosclerosis in patients with type 2 diabetes.