A method for identifying a gene having a role in the presentation of diabetic nephropathy comprises culturing mesangial cells in the presence of a concentration of glucose sufficient to induce differential expression, especially up-regulation, of a gene susceptible to such differential expression and identifying the gene so induced. The cells are also optionally subjected to mechanical strain and/or TGF-.beta.1 can be added to the culture medium. The differentially expressed genes can be identified by suppression subtractive hybridisation. The method has resulted in the Identification of novel genes which play a role in the presentation of diabetic nephropathy. The genes can be used as diagnostic markers for diabetic nephropathy and as the basis of drug development programmes.