Visfatin is an adipocytokine that improves insulin resistance, and has an anti-diabetic effect. However, the role of visfatin in the kidney has not yet been reported. In this experiment, the synthesis and physiological action of visfatin in cultured mesangial cells (MCs) were studied to investigate the role of visfatin in diabetic nephropathy. Visfatin was found synthesized in MCs as well as adipocytes. Visfatin synthesis was markedly increased, not by angiotensin II, but by high glucose stimuli. In addition, visfatin treatment induced a rapid uptake of glucose, peaking at 20min after visfatin treatment in a dose-dependent manner. A small inhibiting RNA, siRNA against insulin receptor significantly blocked visfatin mediated glucose uptake. Visfatin stimuli also enhanced intracellular NAD levels and FK866, which is a specific inhibitor of nicotinamide phosphoribosyltransferase (Nampt), treatment significantly inhibited visfatin-induced NAD synthesis and glucose uptake. Visfatin treatment increased GLUT-1 protein expression in isolated cellular membranes, and pre-treatment of cytochalasin B completely inhibited visfatin-induced glucose uptake. Moreover, immunofluorescent microscopy showed the migration of cytosolic GLUT-1 into cellular membranes after visfatin treatment. In accordance with these results, the activation of protein kinase B (PKB) was detected after visfatin treatment. Furthermore, visfatin treatment dramatically increased the synthesis of profibrotic molecules including TGF1, PAI-1, and type I collagen, and pre-treatment with cytochalsin B completely inhibited visfatin-induced up-regulation of profibrotic molecules. These results suggest that visfatin is produced in MCs, which are a novel target for visfatin, and play an important role in the pathogenesis of diabetic nephropathy.