Plasma glycooxidation protein products in type 2 diabetic patients with nephropathy

Abstract Background In diabetes mellitus, hyperglycaemia accelerates non‐enzymatic glycation and oxidative stress leading to damage of macromolecules, among others proteins. This manifests in the increased levels of advanced glycation end products (AGE) and advanced oxidation protein products (AOPP). Objectives To assess the plasma levels of AGE and AOPP in the patients with type 2 diabetes mellitus (T2DM) and to estimate its relation and connection with the degree of nephropathy. Material and Methods In 121 diabetic patients and 22 healthy people plasma levels of AGE and AOPP were determined with fluorimetric and spectrophotometric methods, respectively. To estimate nephropathy stage, albumin/creatinine ratio was calculated on the basis of albumin and creatinine concentrations in early morning urine samples. Results Diabetic patients had significantly higher levels of AGE and AOPP in comparison to healthy people. Both parameters were increasing progressively from normoalbuminuria, through microalbuminuria to macroalbuminuria. Statistically, the most significant differences were observed in AOPP concentration between separated groups. AGE fluorescence was significantly different on the same low, statistical level between patients with normoalbuminuria when compared to those with micro‐ and macroalbuminuria. Plasma AGE correlated significantly with urinary albumin/creatinine ratio whereas AOPP correlated with plasma creatinine level. Conclusions The connection between plasma levels of both glycooxidation protein products—AGE and AOPP with nephropathy severity, measured by the degree of albuminuria, in T2DM patients was observed. We can suggest that the AOPP better reflect the progression of kidney damage than AGE in examined diabetic patients. Copyright © 2008 John Wiley & Sons, Ltd.