Increased serum level of soluble receptor for advanced glycation end products (sRAGE) in type 2 diabetic patients with nephropathy

Abstract

Activation of the receptor for advanced glycation end products (RAGE) has been implicated in the development of diabetic vascular complications. Soluble RAGE (sRAGE) could act as a decoy for the RAGE ligands and may thus exert a cytoprotective effect. Since RAGE is upregulated by advanced glycation end products (AGEs), the same could be implied for sRAGE. We aimed to investigate the role of sRAGE as a marker of early diabetic nephropathy. Forty-eight type 2 diabetic patients, further subdivided into group 1 without renal affection (10 patients), group 2 with microalbuminuria (25 patients), and group 3 with proteinuria (13 patients), and age-matched control group 4 (17 subjects) were included. Serum sRAGE, urea, creatinine, plasma glycated hemoglobin (HBA1c), and urinary albumin excretion (albumin/creatinine ratio) were measured. sRAGE levels were significantly higher in groups 2 and 3when compared to groups 1 and 4. No significant difference was found on comparing groups 2 and 3 together or on comparing groups 1 and 4. There was a significant positive correlation between sRAGE level and all the studied parameters (p < 0.05) as well as a significant association between the sRAGE positivity within the three diabetic groups and the degree of proteinuria. Although sRAGE level was found to be significantly higher in the microalbuminuria group when compared to both the control and diabetics with normal kidney groups, the absolute value did not differ significantly from the proteinuria group. So we say that sRAGE can be used as a marker of diabetic nephropathy; however, its absolute level cannot be used to distinguish different degrees of renal affection.