Accumulating evidence has demonstrated that major depressive disorder (MDD) and Type 2 diabetes mellitus (T2DM) are two of the most prevalent and devastating diseases,and lead to considerable economic burden and loss of production labor.A substantial body of studies suggested that there is a strong link between depression and T2DM.For example,the prevalence of depression is increased significantly in patients with T2DM compared with those without diabetes [1].In addition,depression appears to increase the prevalence of development of T2DM [2].Hypotheses regarding the link between MDD and T2DM consist of physical and psychological factors.In spite of the evidence that depression is epidemiologically associated with T2DM,the cause of this correlation is still unclear.