Diabetic Nephropathy (DN) with increasing rate of mortality and morbidity is considered as a main cause of End-Stage Renal Disease (ESRD). A wide spectrum of biomarkers exist for early detection of DN, but they suffer from low specificity and sensitivity, indicating the urgent demand of finding more effective biomarkers. Also, the pathophysiology of tubular damage and its relation to DN are not yet completely understood. Kidney Injury Molecule-1 (KIM-1) is a protein which is expressed at substantially low contents in the kidney under physiological conditions. A number of reports have demonstrated the close relationship between urine and tissue KIM-1 levels and kidney disorders. KIM-1 is known as a biomarker for diabetic nephropathy and renal injury. In this study, we aim to review the potential clinical and pathological roles of KIM-1 in diabetic nephropathy.