Lipid peroxidation and antioxidant enzyme activities in erythrocytes of type 2 diabetic patients

BACKGROUND AND OBJECTIVE

Although diabetes mellitus (DM) patients are claimed to be under oxidative stress because of prolonged exposure to hyperglycemia, the influence of glycemic control and cardiovascular complication in diabetes on oxidative stress parameters has not been fully studied. The present study aimed to investigate lipid peroxidation end product (malondialdehyde, MDA) and antioxidant enzymes in fairly controlled type 2 DM (fasting plasma glucose [FPG] < or = 180 mg/dl) or type 2 DM complicated with coronary heart disease (CHD) and poorly controlled type 2 DM (FPG > 180 mg/dl) in comparison to a normal healthy group (FPG < 110 mg/dl).

MATERIAL AND METHOD

MDA and antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were determined in the red cell of 19 subjects with poorly controlled type 2 DM, 26 subjects with fairly controlled type 2 DM and 20 subjects with type 2 DM complicated with CHD who were matched for age and gender. Twenty healthy subjects with normal plasma glucose level and matched for age and gender were served as a control group. In all groups of DM these oxidative stress parameters were compared to a control group by one-way ANOVA test. Pearson rank correlation coefficient was used to compare the relationship between FPG and oxidative stress status in type 2 DM and normal controls.

RESULTS

The red cell MDA levels were significantly higher in all types of diabetes compared to age-matched normal controls. The mean of red cell MDA level was highest in type 2 DM complicated with CHD. Red cell antioxidant enzyme activities were also significantly increased except for SOD and GPx activities in fairly controlled type 2 DM. The significant positive correlation between oxidative stress status (as MDA and CAT) and FPG was found in poorly controlled type 2 DM and type 2 DM complicated with CHD whereas in fairly controlled type 2 DM the significant positive correlation between CAT and FPG was only observed.

CONCLUSION

These findings strongly confirmed the evidence that diabetic patients were susceptible to oxidative stress and higher blood glucose level had an association with free radical-mediated lipid peroxidation. The highest level of MDA in type 2 DM complicated with CHD suggested that oxidative stress played an important role in the pathogenesis of cardiovascular complication. The results also showed the increase in antioxidant enzymes. These could probably be due to adaptive response to pro-oxidant in diabetic state. Hence, there seems to be imbalance between oxidant and antioxidant systems in type 2 diabetic patients.

Glutathione and glutathione peroxidase in type 1 diabetic patients

OBJECTIVE

Diabetic (DM) patients are claimed to be under oxidative stress because of hyperglycemia. The influence of free radical production by this hyperglycemic induction may involve cardiovascular complications in diabetes. The present study aimed to compare the glutathione (GSH) level and glutathione peroxidase (GPx) activity in type 1 DM and a normal healthy group.

MATERIAL AND METHOD

GSH level and GPx activity were determined in red cells of 20 subjects of type 1 DM containing fasting plasma glucose (FPG) > or = 140 mg/dL. Twenty healthy normal subjects with normal plasma glucose level (FPG < or = 110 mg/dL) and matched for gender and age served as the control group. These oxidative stress parameters of type 1 DM were compared to a control group by unpaired student's t-test. The association of these parameters with FPG was performed by Pearson product moment correlation.

RESULTS

The level of red cell GSH was significantly lower in type 1 DM (p = 0.011) but red cell GPx activity was significantly increased (p = 0.003) when compared to age-matched normal control. The decrement of red cell GSH may be due to the higher rate of consumption of GSH, increasing GPx activity or a reduction of pentose phosphate pathway, stimulated by insulin, resulting in lowered GSH recycle. The correlation between FPG and GSH in type I diabetic patients compared with healthy normal subjects was also observed and it was found that there was a negative correlation, but not found between FPG and GPx activity.

CONCLUSION

The present finding suggested that type 1 DM patients were susceptible to oxidative stress and higher blood glucose level had an association with free-radical-mediated lipid peroxidation. Therefore, any means that can reduce oxidative stress may be beneficial for slow progression of cardiovascular complication in type 1 diabetic patients.

Antioxidant status and lipid peroxidation end products in patients of type 1 diabetes mellitus

BACKGROUND AND OBJECTIVE

In Type 1 diabetes mellitus (DM), hyperglycemia is considered a primary cause of diabetic vascular complications and is associated with oxidative stress. The role of antioxidants, particularly alpha tocopherol, in Type 1 DM and its contribution in the development of vascular complications is not clear. Therefore, the present study aims to investigate the relationship between antioxidant status (alpha tocopherol) and lipid peroxidation end products (malondialdehyde; MDA) in the plasma of 20 Type 1 DM and 20 nondiabetic healthy control subjects.

MATERIAL AND METHOD

Lipid levels in all subjects were analyzed spectrophotometrically by enzymatic reagent kits. Plasma MDA was assessed by spectrofluorometry, whereas plasma alpha tocopherol was estimated by high performance liquid chromatography in Type 1 DM as well as in the control subjects of matched sex and ages. The results of Type 1 DM were compared with a control group using unpaired Student's t-test. The correlations between fasting plasma glucose and other laboratory parameters were assessed by Pearson rank correlation coefficient.

RESULTS

The plasma MDA concentration was significantly higher in Type 1 diabetic patients as compared to controls, (p < 0.01). A significantly reduced plasma antioxidant status of Type 1 DM patients was found only in alpha tocopherol / total lipid as compared to controls (p < 0.05). However, no significant difference was observed in plasma a tocopherol and a tocopherol / total cholesterol (p > 0.05) as compared to the control subjects. The positive correlation between MDA and FPG was demonstrated in Type 1 diabetic compared with normal subjects.

CONCLUSION

We conclude that antioxidant supplementation may be necessary for treatment to reduce oxidative stress for diabetic complication protection in Type 1 DM.

Plasma lipid peroxidation and antioxidiant nutrients in type 2 diabetic patients

BACKGROUND AND OBJECTIVE

Observation shows diabetic patients to be more prone to oxidative stress because of hyperglycemia. The elevation of free radical production by this hyperglycemic production may exacerbate cardiovascular complication in diabetes. This study aims to investigate the oxidative stress related parameters in type 2 DM. Since the effects of glycemic control and cardiovascular complications in DM on these parameters has been not fully determined, the comparison between plasma MDA (malondialdehyde) and antioxidant nutrients with their age-matched normal healthy group may be used to determine the susceptibility of oxidative stress in this type of DM.

MATERIAL AND METHOD

MDA and antioxidant nutrients (vitamin A, C, E and beta-carotene) were analyzed in plasma of 19 subjects with poorly controlled type 2 DM (fasting plasma glucose [FPG] > 180 mg/dl), 26 subjects with fairly controlled type 2 DM (FPG < or = 180 mg/dl), and 20 subjects with type 2 DM complicated coronary heart disease (CHD) who were matched for age and gender. Twenty healthy subjects with normal plasma glucose level (FPG < 110 mg/dl) and matched for age and gender served as a control group. In all groups of DM these oxidative stress parameters were compared to a normal group.

RESULTS

The plasma MDA levels were significantly higher in all types of DM compared to age-matched normal control. Plasma antioxidant vitamin C and E significantly lower only in poorly controlled and CHD complicated type 2 DM, respectively. The mean of plasma vitamin E level was lowest in type 2 DM complicated with CHD. No significant differences in both plasma vitamin A and beta-carotene were noted between any types of DM and age-matched normal healthy group. The positive correlation between MDA and FPG was demonstrated in most group of patients with their normal subjects except in fairly controlled type 2 DM and negative correlation between vitamin E and FPG was also demonstrated in type 2 DM with CHD.

CONCLUSION

These findings suggested that diabetic patients were susceptible to oxidative stress and higher plasma glucose level had an association with free radical-mediated lipid peroxidation. The lowest level of vitamin E in type 2 DM complicated with CHD indicated that oxidative stress played an important role in cardiovascular complication and vitamin E supplementation may be necessary for treatment and prevention in this group of diabetics.