Corresponding author: Ammar A.Y. Almulathanon ( ammara@uomosul.edu.iq ) Academic editor: Georgi Momekov
© 2021 Ammar A.Y. Almulathanon, Jehan A. Mohammad, Fatimah Haitham Fathi.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Almulathanon AAY, Mohammad JA, Fathi FH (2021) Comparative effects of metformin and glibenclamide on the redox balance in type 2 diabetic patients. Pharmacia 68(2): 327-332. https://doi.org/10.3897/pharmacia.68.e63365
|
It is known that there is a strong association between oxidative stress and insulin resistance in type 2 diabetes mellitus (T2DM). Although the role of glibenclamide in diabetes treatment has been evaluated, there is only limited evidence about its antioxidant effects in diabetic patients. Moreover, previous studies showed discrepant results regarding the effects of metformin on antioxidant/ oxidant parameters in type 2 diabetic patients. The present study aimed to evaluate the effects of metformin versus glibenclamide on oxidative stress biomarkers, represented by serum malondialdehyde (MDA), nonenzymatic, and enzymatic antioxidants in type 2 diabetic patients. Forty-six patients with T2DM participated in this study and categorized into 3 groups, Group A included 17 newly diagnosed diabetic patients, group B included 15 diabetic patients received metformin monotherapy (1000 mg/day) for up to 1 year and group C included 14 diabetic patients received glibenclamide monotherapy (5 mg/day) for up to 1 year. Serum MDA, catalase (CAT), vitamin C, E, and reduced glutathione (GSH) were measured. We found significantly lower concentrations of MDA and significantly higher antioxidant levels (CAT, GSH, vitamin C, and E) in the metformin-treated group compared to the glibenclamide counterpart. Our data confirmed that metformin has a more beneficial effect on oxidant/antioxidant status compared to glibenclamide, therefore, provides protection against reactive oxygen species (ROS) induced oxidative damage during diabetes.
Antioxidant, Diabetes, Glibenclamide, Metformin, Oxidative stress
Type 2 diabetes mellitus (T2DM), a chronic metabolic disorder, makes up over 90% of all cases of diabetes and it is characterized by hyperglycemia due to disturbances in insulin synthesis and efficiency (
Oxidative stress reflects a disturbance in the balance between reactive oxygen species (ROS) production and the antioxidant defense mechanisms (
The cornerstones of diabetes management include lifestyle modifications in combination with pharmacological therapy. Sulfonylureas, biguanides, meglitinides and thiazolidinediones are currently available oral antidiabetic agents that can improve glycemic control either in combination or as individual agent (
Oxidative stress has a crucial contribution in the development of diabetes and its complication (
To our knowledge, there is only a little information about the antioxidant effects of glibenclamide in type 2 diabetic patients. Moreover, previous clinical studies of metformin on the oxidant /antioxidant balance have yielded conflicting results (
UV-VIS Spectrophotometer PD-303 UV (APEL brand, Japan) and ELx 800 Universal Microplate Reader (BioTek, USA) were used.
Thiobarbituric acid (TBA) was obtained from (Cayman, USA). Metformin (Siofor 500) was purchased from Berlin Chemie (Germany). Glibenclamide (Glibesyn) was obtained from, Medochemie (Cyprus). FSG was determined by kit purchased from BIOLABO (France). Insulin AccuBind ELISA Kit was obtained from Monobind (USA). All other chemicals were purchased from Sigma Aldrich (USA).
A retrospective crosssectional study was conducted on patients with T2DM in Al-Waffaa Centre of Diabetes Management and Research, Mosul, Iraq. It was done between October, 2019 and January, 2020. This study included 46 patients with T2DM of both sexes aged between 32 and 56 years. It was approved by the Research Ethics Committee of College of Pharmacy, University of Mosul. Informed consent was obtained from all participants before their inclusion into the study, and the whole study process was performed in accordance with the last update of the Declaration of Helsinki. The participants were categorized into three groups, Group A included 17 newly diagnosed diabetic patients, group B included 15 patients received metformin monotherapy (1000 mg/day) for up to 1 year and group C included 14 patients received glibenclamide monotherapy (5 mg/day) for up to 1 year. Diagnosis of T2DM was made according to the World Health Organization and American Diabetic Association criteria. Pregnant and lactating women, patients receiving additional drugs, vitamins, or supplements, patients with medical conditions other than type 2 diabetes, alcoholics, smokers, and patients who underwent medication changes during the period of treatment were excluded from the study. Anthropometric variables such as height and weight were obtained to calculate the body mass index (BMI).
Venous blood samples were collected from each diabetic patient after overnight fasting in plain tubes. Following an incubation period of 10 min in a water bath at 37 °C, sera were separated by centrifugation at 4,000× g for 10 mins and then aliquoted and stored at -20 °C to be analyzed later, except for serum glucose level which was estimated immediately.
Fasting serum glucose (FSG) was estimated by the enzymatic colorimetric method and the absorbance was measured at 505 nm. Serum insulin was measured by enzyme-linked immunosorbent assay (ELISA) and the absorbance was determined at 450 nm. Insulin resistance was assessed by the homeostatic model assessment (HOMA-IR) according to the following equation:
HOMA-IR = Insulin (micro units (µU) / mL) × Glucose (mmol/L) / 22.5 (
Serum MDA was evaluated by the modified method,(
CAT activity in serum was determined by measuring the decrease in hydrogen peroxide absorbance at 240 nm wavelength using the spectrophotometric method (
GSH in serum was estimated according to the modified standard Ellman method (
Vitamin C in serum was determined by measuring a decrease in the absorption of 2,6-dichlorophenolindophenol at 520 nm (
Mann Whitney test and Kruskal-Wallis test followed by a Dunn’s multiple comparisons test were performed to compare two or multiple datasets, respectively. Spearman rank correlation analysis was used to determine associations between MDA with other laboratory parameters. All values were expressed as mean±SD and statistical significance was established when p < 0.05. All analyses were conducted using Graphpad prism software version 8.0 (San Diego, California, USA).
Demographic characteristics of newly diagnosed and treated diabetic groups
Table
Parameter(unit) | Newly diagnosed T2DM | Metformin | Glibenclamide |
---|---|---|---|
Age (years) | 40.47±6.634 | 43.07±7.245 | 41.79±7.029 |
BMI (kg/m2) | 25.07±1.167 | 24.59±0.9819 | 24.54±1.201 |
Duration of treatment (months) | – | 7.100±3.146 | 7.286±2.847 |
Metformin treated group showed significantly lower FSG level and HOMA-IR index compared to the untreated and glibenclamide treated patients. However, a significant elevation in insulin level was observed in the glibenclamide treated patients compared to other groups (Table
Parameter(unit) | Newly diagnosed T2DM | Metformin | Glibenclamide |
---|---|---|---|
FSG (mmol/l) | 12.21± 1.064 | 8.787±0.5167a****, b** | 10.88±0.7934 |
Insulin(μu/L) | 8.741±0.7289 | 9.167±0.4835 | 9.393±0.5240a* |
HOMA-IR | 4.732±0.4748 | 3.574±0.1834a****, b**** | 4.530±0.2562 |
It was observed that the MDA level was significantly decreased in the metformin- treated patients compared to glibenclamide and untreated groups (Figure
Effects of metformin and glibenclamide on serum MDA level. The results are expressed as mean±SD.* indicates statistically significant differences in contrast to newly diagnosed group (***p < 0.001); # indicates statistically significant differences between treated groups (##p < 0.01), as determined by Kruskal-Wallis test followed by a Dunn’s multiple comparisons post-hoc test.
Effects of metformin and glibenclamide on serum levels GSH, vitamin C and vitamin E. The results are expressed as mean±SD. * indicates statistically significant differences in contrast to newly diagnosed group (**p < 0.01; ****p < 0.0001); # indicates statistically significant differences between treated groups (#p < 0.05; ##p < 0.01; ###p < 0.001), as determined by Kruskal-Wallis test followed by a Dunn’s multiple comparisons post-hoc test.
Moreover, the result analysis revealed that both metformin and glibenclamide treated groups have significantly higher catalase levels compared to the untreated group. However, metformin resulted in a significantly higher catalase level than glibenclamide (Figure
Effects of metformin and glibenclamide on serum catalase level. The results are expressed as mean±SD. * indicates statistically significant differences in contrast to newly diagnosed group (**p < 0.01; ****p < 0.0001); # indicates statistically significant differences between treated groups (#p < 0.01), as determined by Kruskal-Wallis test followed by a Dunn’s multiple comparisons post-hoc test.
The association of MDA with other laboratory parameters in metformin-treated group has been examined. MDA showed a significant negative correlation with vitamin C and vitamin E (Table
While metformin and glibenclamide have frequently been used in T2DM, studies focused on their effects on oxidative stress have shown discrepant results. The present study was done to assess the effects of metformin and glibenclamide on lipid peroxidation and antioxidant level in type 2 diabetic patients. In this study, although metformin exhibited a nonsignificant increase in insulin production, FSG, and HOMA-IR level were found significantly lower compared to the glibenclamide and untreated group (Table
Depletion of antioxidants and increased lipid peroxidation are features of diabetes mellitus (
Various enzymatic and nonenzymatic antioxidants are produced in the body to counteract oxidative stress through detoxification of ROS (
On Spearman’s correlation analysis, FSG, insulin, and HOMA-IR showed a nonsignificant relationship with MDA and antioxidants in metformin-treated group (data not shown), whereas a significant negative correlation has been found between MDA and nonenzymatic antioxidants (vitamin C and vitamin E) in this group (Table
It should be noted that our study has some limitations. Glycated hemoglobin (HbA1c) was not measured. Moreover, the number of diabetic patients participate in this study was low. Other studies on larger sample sizes are recommended for more confirmation.
The present study revealed that metformin monotherapy was more effective in ameliorating oxidative stress and improving the antioxidant defense systems compared to glibenclamide in type 2 diabetic patients, thus provide protection against oxidative stress-induced injury during diabetes and its complications.
The authors would like to thank the University of Mosul, and especially the College of Pharmacy, for their support in providing the equipment and laboratories to accomplish this research.