Objective: To investigate the role and mechanism of adrenomedullin (AM) in diabetic nephropathy. Methods:This research observed the changes of the expression and secretion of AM, TGF-β1 in the cultured human mesangial cells under high glucose conditions and the contents of the laminin and type Ⅳ collagen in the supernatants, and the effect of intervention with AM on the changes.Results: High glucose condition resulted in increase in the expression and secretion of AM, TGF-β1, laminin and type Ⅳ collagen, and AM could reverse the influence of high glucose on the cultured human mesangial cells. Conclusion: The results showed that high glucose condition in one of the stimulating factors of AM, and the renal protective action of AM may be associated with suppression of TGF-β1 and reducing excessive accumulation of laminin and type Ⅳ collagen.