Adiponectin has been reported to have a wide range of antiatherogenic actions. Two common single nucleotide polymorphisms (SNPs) at the adiponectin locus (45T>G and 276G>T) have been reported to be associated with diabetes and cardiovascular diseases. The aim of this study was to examine the association between common polymorphisms of the adiponectin gene (ACDC) and carotid atherosclerosis in patients with type 2 diabetes mellitus. A total of 708 unrelated patients with type 2 diabetes mellitus were recruited. SNP45 and SNP276 ACDC were genotyped, and B-mode ultrasonography of the carotid arteries was performed to measure carotid intima-media thickness and assess the presence of carotid artery plaques (CAP). Although there was no significant difference in carotid intima-media thickness according to ACDC genotype, subjects carrying the SNP45 GG genotype had a significantly higher risk of having CAP (odds ratio, 2.468; P = .045) compared with carriers of the T allele after adjustment for possible confounding factors. This study suggests that the GG genotype at ACDC SNP45 is associated with the presence of CAP and may contribute to atherosclerosis in type 2 diabetes mellitus.