Background Brain-derived neurotrophic factor(BDNF)Val66Met polymorphism is reported to be associated with cognitive dysfunction, an important comorbidity factor in patients with type 2 diabetes mellitus (T2DM), especially in elderly populations, however, the underlying pathophysiological mechanisms are unclear. Aim This study was performed to investigate the association betweenBDNFVal66Met polymorphism and mild cognitive impairment (MCI) in elderly patients with T2DM. Methods In total, 105 MCI and 105 normal cognition controls of T2DM patients were enrolled; all of the patients underwent neuropsychological assessments.BDNFVal66Met polymorphism was genotyped via TaqMan SNP genotyping assay. Data from clinical and laboratory-based examinations were collected. Results The frequency of theBDNFMet allele was significantly higher in the MCI group than in the controls. Multiple regression analysis indicated an association of the Met allele with MCI in patients with T2DM (OR = 2.54; 95% CI 1.33-4.84;p = 0.005). Stratified by educational level, theBDNFMet allele was significantly associated with MCI in elderly T2DM patients (OR = 3.29; 95% CI 1.26-8.57;p = 0.015) among the group of low educational levels (< 12 years); however, the association was insignificant among those with higher educational levels. Discussion BDNFMet allele carriers showed a higher frequency of MCI than Val/Val homozygotes in elderly T2DM patients. However, this association was only significant in patients with low education levels. Conclusion BDNFVal66Met polymorphism may have a potential role in MCI in elderly T2DM patients, especially those with low educational levels.