Objective: To investigate anti-diabetic properties of the plant extract known as GUH in comparison to commercially available drugs metformin and rosiglitazone. Methods: Male Wistar rats were fed a maintenance diet (MD) with tap water or a high fat diet (HFD) with sucrose solution for a period of twelve weeks. Thereafter a separate groups of animals were then treated with GUH at 5 different dose levels, metformin or rosiglitazone for twelve weeks. Food intake, liquid intake, weights, blood glucose, and insulin were monitored throughout the treatment period. An intravenous glucose tolerance test (IVGTT) was performed on representative animals from each treatment group prior to termination. At termination blood was taken and total cholesterol, tri-acylglycerol (TAG), low density lipoproteins LDL, and high density lipoproteins (HDL) were measured. Results: The effect of GUH in MD fed rats was not marked. However, food intake and weight gain and total cholesterol were lower than in control animals. In HFD fed animals GUH, metformin and rosiglitazone had a significant effect The extract reduced blood glucose and increased circulating insulin levels when compared to controls but results were not significantly different to metformin and rosiglitazone treated animals. As with metformin and rosiglitazone, GUH increased food intake with a concomitant weight increase. This weight increase was, nevertheless, less than with the other 2 treatments. In HFD fed animals GUH at the highest dose level increased the glucose clearance rate to a greater extent than metformin and rosiglitazone. Conclusion: The results conclusively show that the extract GUH was at least as effective, and in some instances more effective, than currently used diabetes treatments. Although further work is required to investigate the mode of action, it is evident that extracts of indigenous South African plants can be cost effective and efficacious treatments.
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