A study performed in rats has shown antidiabetic properties of stevia rebaudiani.
The rats were separated into 8 groups of 10 each. Four of the groups were injected with streptozocin, a known diabetogen which acts to selectively destroy beta cells and consequently caused a marked reduction in insulin levels. Groups also varied in the source of stevia including: stevia leaves powder, stevia leaves fiber, and stevia leaves polyphenols.
Rats receiving streptozocin with no stevia showed a significant increase in the cardinal signs of diabetes: polydipsia, polyphagia, and polyuria. Food consumption increased from 65g to 91g/week, water intake nearly doubled from 27ml/day to 59ml/day, and urine output increased from 39ml/day to 98ml/day. However, rats that were pre-fed with stevia leaves powder and polyphenol extract before injection of strepotozocin showed significantly less of an increase in food consumption, water intake, and urine output.
In the stevia leaves powder and its polyphenol extract groups, food consumption was brought down by 15% and 18%, water intake by 28% and 12%, urine output by 42% and 54%, respectively. Stevia leaves powder and its polyphenol extract also demonstrated a blood glucose reduction of 36 and 64%, respectively, from the elevated levels.
These findings did not parallel those in the stevia fiber fed rats, which showed no reduction in blood glucose levels.
The results of this study also showed an increased serum insulin level in the stevia leaves powder and its polyphenol extract groups, suggesting stevia might have a role in enhancing the number of beta cells in the pancreas of diabetic patients. Other proposed mechanisms for the benefits of stevia on hyperglycemia include modulation of glucose transport or glucose disposal. Further benefits of stevia reported in this study include renal protection and antioxidant properties.
Naveen Shivanna, Mahadev Naika, Farhath Khanum, Vijay K. Kaul. Antioxidant, anti-diabetic and renal protective properties of Stevia rebaudiana. Journal of diabetes and its complications 1 March 2013 (volume 27 issue 2 Pages 103-113 DOI: 10.1016/j.jdiacomp.2012.10.001)