Monocyte/macrophage recruitment correlates strongly with the progression of renal impairment in diabetic nephropathy (DN), yet their direct role is not clear. We hypothesize that macrophages contribute to direct podocyte injury and/or an abnormal podocyte niche leading to DN. Experiments were conducted in CD11b-DTR mice treated with diphtheria toxin (DT) to deplete macrophages following streptozotocin (STZ) induced diabetes. Additional experiments were conducted in bone marrow chimeric (CD11b-DTR-> C57BL6/J) mice. Diabetes was associated with an increase in the M1/M2 ratio by 6 weeks following induction of diabetes. Macrophage depletion in diabetic CD11b-DTR mice significantly attenuated albuminuria, kidney macrophage recruitment, glomerular histologic changes and preserved kidney nephrin and podocin expression compared with diabetic CD11b-DTR mice treated with mutant DT. These data were confirmed in chimeric mice indicating a direct role of bone marrow-derived macrophages in DN. In vitro, podocytes grown in high glucose media significantly increased macrophage migration compared to podocytes grown in normal glucose media. In addition, classically activated M1 macrophages; but not M2 macrophages; induced podocyte permeability. These findings provide evidence that macrophages directly contribute to kidney injury in DN; perhaps by altering podocyte integrity through the pro-inflammatory M1 subset of macrophages. Attenuating the deleterious effects of macrophages on podocytes could provide a new therapeutic approach to the treatment of DN.