Recently, a number of studies have reported the association between the single nucleotide polymorphisms (SNPs) +45 T>G polymorphism in the adiponectin (ADIPOQ) gene and type 2 diabetes mellitus (T2DM) risk, though the results are inconsistent. In order to obtain a more precise estimation of the relationship, a meta-analysis was performed. In this current study, the Medline, Embase, Pubmed, ISI Web of Knowledge, Ovid, Science Citation Index Expanded Database, Wanfang Database, and China National Knowledge Infrastructure were searched for eligible studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association. Forty-five publications were included in the final meta-analysis with 9986 T2DM patients and 16,222 controls for ADIPOQ +45 T>G polymorphism according to our inclusion and exclusion criteria. The +45 T>G polymorphism was associated with an overall significantly increased risk of T2DM (G vs. T: OR = 1.18, 95% CI = 1.06-1.32; The dominant model: OR = 1.18, 95% CI = 1.03-1.33; The recessive model: OR = 1.47, 95% CI = 1.20-1.78; The homozygous model: OR = 1.62, 95% CI = 1.25-2.09; Except the heterozygous model: OR = 1.11, 95% CI = 0.98-1.24). Subgroup analysis revealed a significant association between the +45 T>G polymorphism and T2D in an Asian population. Thus, this meta-analysis indicates that the G allele of the ADIPOQ +45 T>G polymorphisms associated with a significantly increased risk of T2DM in the Asian population.