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.

Lycopene: A Potent Antioxidant for the Amelioration of Type II Diabetes Mellitus

“…The relationship between T2DM and oxidative stress has been highlighted in numerous experimental studies through the measurement of oxidative stress biomarkers in T2DM patients. As shown in Table 1 , the enzymatic antioxidant GPx was significantly decreased in T2DM patients compared to controls [ 34 , 35 , 36 , 37 , 38 ]. SOD activity was reduced in the study conducted by Al-Jiffri [ 34 ] and Mandal et al [ 39 ], increased in the study by Aouacheri et al [ 35 ], and remains unchanged in the study by George and colleagues [ 40 ].…”

“…On the contrary, pre-T2DM and T2DM patients showed higher lipid peroxidation levels as reflected by higher MDA and TBARS levels compared to the controls in majority of the studies. In terms of the effect of glycemic control on antioxidant capacity, reduced TAC and GPx along with an increased MDA level were observed in T2DM with good and poor glycemic control compared to controls [ 36 ]. T2DM patients with non-alcoholic steatohepatitis (NASH) had a significantly higher level of MDA compared to T2DM without NASH and healthy controls [ 41 ].…”

The Importance of Antioxidant Activity for the Health-Promoting Effect of Lycopene

“…Picu et al [142] found that SOD activity did not change. Patients with type 2 diabetes had decreased levels of GSH and CAT [137,[139][140][141][142]. Malondialdehyde, a marker of oxidative stress, was increased in people with this disease [137][138][139][140][141].…”

“…Many studies confirm the connection between type 2 diabetes and oxidative stress. This relationship was determined by examining biomarkers of oxidative stress in patients with type 2 diabetes [137][138][139][140][141][142]. People with type 2 diabetes had lower glutathione peroxidase activity compared to people in the control group [137,139,140,142].…”

“…This relationship was determined by examining biomarkers of oxidative stress in patients with type 2 diabetes [137][138][139][140][141][142]. People with type 2 diabetes had lower glutathione peroxidase activity compared to people in the control group [137,139,140,142]. Jiffri et al [139] and Mandal et al [141] observed less superoxide dismutase activity.…”