Effects of Co-Administration of Metformin and Vitamin C or E on the Blood Glucose Levels and Lipid Profiles of Streptozotocin-Induced Diabetic Rats

[Speaker] Adaeze P Uchendu:1
[Co-author] Eric K. I. Omogbai:1, Ighodaro Igbe:1, Chidi Obodozie:1
1:Pharmacology & Toxicology, University of Benin, Benin City, Edo State, Nigeria

Diabetes mellitus is a chronic, progressive metabolic disorder characterized by hyperglycemia, oxidative stress, inflammation and insulin resistance. Free radical-induced oxidative stress plays a significant role in the pathogenesis of diabetes mellitus. Oxidative stress plays an important role in the development of vascular complications particularly in type 2 diabetes. This study investigated the effects of co-administration of metformin and vitamin C or E on blood glucose and serum lipid levels in streptozotocin-induced diabetic rats.
Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (40 mg/kg body weight) in male wistar rats fasted overnight. Animals with fasting blood glucose levels above 200 mg/dl were confirmed diabetic after 48 hours and were used in the study. Diabetic rats were randomly divided into 6 groups of 5 rats each. The treatments were as follows: non-diabetic rats received distilled water (0.5 ml/day), diabetic rats received vitamin C alone (1000 mg/kg), vitamin E alone (600 mg/kg), metformin alone (500 mg/kg), metformin (500 mg/kg) plus vitamin C (1000 mg/kg) and metformin (500 mg/kg) plus vitamin E (600 mg/kg). The animals were treated orally once daily for two weeks and blood samples were collected at various time intervals for blood glucose levels and lipid profiles evaluations. Statistical analysis was done using one-way ANOVA followed by Dunnett's post-hoc test of multiple comparisons (GraphPad Prism 6, San Diego, USA). The P - value was set at P< 0.05 for significant difference
The results showed that vitamin C alone, vitamin E alone, and metformin alone produced significant and comparable reductions in blood glucose levels on both day 7(P<0.05, P<0.01) and day 14 (P<0.001). However, the combinations, metformin plus vitamin C and metformin plus vitamin E caused further reductions in blood glucose levels, total cholesterol, and triglycerides. All treatments prevented diabetes induced-weight loss throughout the study when compared with diabetic control.
These results have demonstrated the positive synergistic effects of combining metformin and antioxidants (vitamin C or E) on blood glucose levels and lipid profiles in type II diabetes
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