TCF7L2 and type 2 diabetes mellitus: These results, on the one hand, suggested that BMI may be a possible factor to impact on the effect of TCF7L2 gene on T2DM by a indirect action; on the other hand, were difficult for us to explain the deep-seated reasons that how the BMI influence the effect of TCF7L2 gene on T2DM because we cannot gain the original data of BMI in each article.