Glycemic control and its impact on oxidative stress biomarkers in type 2 diabetic patients treated with metformin: a cross-sectional analysis

Abstract

AIMS: Evidence shows that diabetic patients may be predisposed to oxidative stress owing to increased glyco-oxidation and lipid peroxidation processes in consequence of chronic hyperglycemia. However, there is dearth of information whether glycemic control positively affects the antioxidant defense system in type 2 diabetes mellitus (T2DM). We investigated the potential association between glycemic control and oxidative stress biomarkers in controlled and uncontrolled diabetic states. METHODS: After obtaining ethical clearance, we included patients receiving metformin with glycated hemoglobin A1c ˂7.0% (glycemic control); newly diagnosed T2DM patients without glycemic control with hemoglobin A1c ˃7.0%; and apparently healthy normoglycemic individuals. The following biomarkers were determined: fasting glycemia level, malondialdehyde, glutathione peroxidase activity, catalase activity, total antioxidant capacity and total cholesterol level. The comparisons between the groups were made by ANOVA. RESULTS: The participants were 260 in number: 80 with controlled diabetes, 80 uncontrolled and 100 controls. All participants were between 40 and 71 years old. Fasting glycemia level and hemoglobin A1c showed significant reductions (p<0.05) in controlled T2DM against the uncontrolled T2DM group, all the same both were significantly higher (p<0.05) against the controls. Likewise, malondialdehyde levels showed significant elevations (p<0.05) correspondingly in both uncontrolled and controlled T2DM against the controls, accompanied with significant reductions (p<0.05) in the antioxidative enzyme activities (glutathione peroxidase activity and catalase activity) and total antioxidant capacity levels against the controls. In addition, total cholesterol was significantly reduced (p<0.05) in controlled T2DM against both uncontrolled T2DM and controls, respectively. There were significant correlations between hemoglobin A1c and oxidative stress biomarkers (p<0.05). CONCLUSION: There was no remarkable difference in oxidative stress states between glycemic controlled and uncontrolled T2DM, despite differences in their fasting glycemia and glycated hemoglobin levels. Our data, therefore, suggest that chronic hyperglycemia and possibly anti-diabetic medicationmay both equally associate with oxidative stress.