Efficacy of Co-administration of Metformin and Propranolol on Oral Glucose Tolerance Test, Blood Glucose and Antioxidative Status of Alloxan-induced Diabetic Rats

Background: Diabetes mellitus (DM) is one of the most prevalent chronic metabolic diseases, and its high prevalence suggests an increased incidence of co-morbidities such as hypertension and heart failure which consequently may require the use of propranolol as a therapeutic agent. Studies have found that patients with diabetes mellitus are 20% more likely to be managed for anxiety disorders at some point in their lives. Many of these patients may be placed on propranolol to manage their anxiety symptoms. Propranolol is however also known to mask the symptoms of hypoglycemia which may occur in the course of diabetic management. Aim: This study therefore sought to investigate the effect of co-administration of metformin and propranolol on alloxan-induced diabetic rats. Method: Diabetes mellitus was induced by single dose injection of 150 mg/kg of alloxan monohydrate. Diabetic rats were divided into four groups: group 1 served as normal control, group 2 as diabetic control, while groups 3 and 4 were treated with metformin and metformin plus propranolol respectively for fourteen days. Fasting blood glucose levels were measured and animals were sacrificed with samples taken for biochemical analysis. Results: Metformin significantly decreased blood glucose level at 60 and 120 minutes after glucose loading, and after 14 days in alloxan-induced diabetic rats, although blood glucose level was much decreased with the combination of metformin and propranolol (MET+PRO). There was remarkable increase in superoxide dismutase with a decrease in malondialdehyde level. Conclusion: This study showed that the co-administration of metformin and propranolol effectively reduced blood glucose level compared with metformin alone while improving antioxidant status in diabetic condition.