We review the validity of the evidence for an association between depression and the risk of insulin resistance (IR). We describe the potentially plausible biological and behavioral mechanisms that explain how depression increases the risk of IR and consequent overt diabetes. We have identified gaps in the literature to guide future research. Evidence for bidirectional associations between depression and IR is inconsistent. Results showing positive associations between depression and IR are derived from cross-sectional studies, whereas negative findings are typically reported in cohort studies. On the other hand, tentative trial evidence suggests that the effective treatment of depression can improve IR, and that lifestyle programs improve IR and reduce depressive symptoms. These emerging themes could lead to potential new multidisciplinary approaches to preventing diabetes. ; Naomi Silva, Evan Atlantis, Khalida Ismail