The determination of AGE-peptides by flow injection assay, a practical marker of diabetic nephropathy

Abstract

Background: Increasing evidence has suggested that advanced glycation end products (AGEs) might play a central role in the pathogenesis of diabetic complications. Serum AGEs concentration may serve as a useful marker for monitoring pathological processes and progression of diabetic complications. Methods: A flow injection assay (FIA) system was developed using high performance liquid chromatography (HPLC) to detect low molecular mass AGEs (AGE-peptides, AGE-P). Serum from diabetic patients ( n=126), normal controls ( n=54) and diabetic mice ( n=20) and matched controls ( n=20) were collected. Results: The coefficient of variance for intra-assay and inter-assay were 1.2% and 6.3%, respectively. The range of recoveries was 94.9–101.9%. The serum AGE-P concentration was significantly increased both in diabetic patients (2.976±0.247 vs. 1.385±0.131 U/ml, P<0.0001) and mice (6.71±0.50 vs. 2.49±0.10 U/ml, P<0.0001) than their respective controls. Concentration of AGE-P was positively correlated with serum creatinine (Scr) ( r=0.7133, P<0.0001), 24-h urinary protein (24-h UPro) ( r=0.8704, P<0.0001) and urinary albumin excretion (UAE) ( r=0.5989, P<0.0001). Conclusions: The present study suggested that FIA might be a reliable method for measuring the serum AGE-P. Furthermore, our results supported the notion that AGE-P might be a valuable marker for predicting the severity of diabetic nephropathy (DN).