Monitoring of markers of glycation, oxidative stress and antioxidant enzymes in relationship to glycemic control in patients with type 2 diabetes mellitus

Increased glycation and oxidative stress plays an important role in the development of micro- and macrovascular diabetic complications. In this study, parameters of glycation and oxidative stress and antioxidant enzymes in relationship to glycemic control in patients with type 2 diabetes mellitus were investigated. Markers of glycation (HbA1c, AGEs), oxidative stress markers (AOPP, LP), antioxidant enzymes (SOD, GPx, CAT) and TEAC were assessed in 81 patients with DM2 (47 patients with good glycemic control (GC group), 34 patients with poor glycemic control (PC group) and 20 healthy blood volunteers. Established spectrofluorimetric and spectrophotometric methods were used to quantify glycative and oxidative stress markers in plasma/erythrocytes. Our results showed that levels of AOPP and AGEs were significantly increased and SOD activity was significantly decreased in PC group compared to control and GC group. The GPx activity was lower in PC group compared to control and GC group, but differences did not reach a significant statistical power. We found negative correlation between HbA1c and SOD activity in PC group. These results confirm presence of increased glycative and oxidative stresses and decreased antioxidant defense in all patients with DM2, especially in patients with poor glycemic control. We suggest that the measurement of not only HbA1c but also fluorescent AGEs, AOPP and SOD activity may be useful to predict the risk of development of diabetic complications. The spectrofluorimetric and spectrophotometric techniques used in our study for assessment of AGEs and AOPP are simple, fast and inexpensive so they can be applicable on large sample size analysis in current laboratory practice, for evaluating glycative and oxidative stresses.