Aim To investigate the association between a 1562C→T mutation of matrix metalloproteinase-9 (MMP-9) gene and carotid artery arteriosclerosis in type 2 diabetes mellitus (T2DM) of Guilin. Methods A case-control study for 158 Guilin Han Chinese subjects (including 98 type 2 diabetes mellitus and 60 normal control) was performed. The number of the 1562 C→T mutation alleles were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results The frequencies of genotype and allele showed no significant difference between control groups and T2DM group, and the frequency of the T genotype and T allele at 1562 were significantly higher in T2DM with carotid artery arteriosclerosis group than in T2DM without carotid artery arteriosclerosis group and control subjects (P<0.05). The analysis showed that MMP-9 T allele was an important risk factor of carotid artery arteriosclerosis in T2DM(OR=2.160, 95%CI:1.026～4.547). Conclusion The T allele of C1562T polymorphism of MMP-9 gene is related to carotid artery arteriosclerosis in Guilin T2DM. The T allele may be a risk factor.