Objectives: The assessment of the clinical significance of adenosine, adenine, inosine, xanthine, hypoxanthine and uric acid concentrations in patients with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) for the detection of the relationship between purine metabolites and disease. Design and methods: The study group consisted of 119 subjects which were divided into three groups: control (n=31), type 2 diabetes without nephropathy (DM, n=23) and with nephropathy (DN, n=65). Levels of related metabolites were measured in plasma of all participants. Results: There is a significant increase of levels of adenosine (P<0.001), inosine (P<0.001), xanthine (P=0.012) and uric acid (P=0.016) with DN compared to DM. The level of xanthine oxidase (reflected by the uric acid: xanthine) did not change. Conclusion: The levels of adenosine, inosine, uric acid and xanthine may be useful for monitoring the progression of DM and evaluating the treatment.,c, 2008 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.