Antihyperglycaemic and Antihyperlipidemic Effect of Gymnema Sylvestre in Protracted Diabetes Mellitus in Wistar Rats

Abstract

Introduction: Dysregulation in glucose and lipid metabolism have been observed in the early phases of Diabetes Mellitus (DM) which may further lead to insulin resistance and beta-cell failure. Effective control of these metabolic alterations may delay the clinical onset of diabetes. A proven herbal medication with antihyperglycaemic activity used in the treatment of Diabetes is Gymnema sylvestre (GSE). An extensive study regarding its benefits in treating long standing diabetes and associated dyslipidemia is obligatory. Aim: To study the effects and optimal dosage of a standardized hydroalcoholic leaf extract of GSE on glycaemic and lipid parameters in diabetic rats. Materials and Methods: Wistar rats of either sex were divided into five groups with eight rats in each group. Single dose of Streptozotocin (STZ) (50mg/Kg body weight) was used to induce DM. The diabetic rats were treated with two oral doses of the GSE at 1g and 2.5 g/kg body wt/day and Glibenclamide (Glb) (500 µg/kg body weight) for a period of 16 weeks. Fasting Blood Glucose (FBG) was checked at day-1 and at the end of 16 weeks. Plasma glycated Haemoglobin (HbA1c), serum insulin, serum Triacylglycerol (TG), Total Cholesterol (TC) and High Density Lipoprotein fraction of Cholesterol (HDL-C) were measured at the end of the study. Statistical analysis was done using the software SPSS-20. Results: Significant decrease in FBG in a dose dependent manner was observed along with increase in serum insulin and decrease in HbA1c levels. Treatment with GSE decreased TG levels significantly and was comparable with Glb. Improvement in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was not significant, but that of Triglyceride Glucose Index (TGI) was significant. GSE at the dose of 2.5g/kg body weight showed a positive correlation between HOMA-IR and TGI (p=0.01) and was comparable with the results of Glb. Conclusion: GSE had a sustained and dose dependent effect in improving glycaemic parameters and TG in diabetic rats of protracted duration. Insulin resistance did not vary significantly from the diabetic control rats.

Keywords

• diabetic rats
• insulin resistance
• lipid profile
• streptozotocin