Characterization of the hypoglycemic effect of Gymnema inodorum and association study of rage gene polymorphisms and diabetic complication in Thai population

Abstract

The effects of Gymnema inodorum (GI) tea consumption on glucose absorption and liver toxicity were evaluated in this study. The study was done in 73 healthy subjects of both sexes, aged between 18-25 years, who have normal fasting glucose level. Standard oral glucose tolerance test (OGTT) was used as a tool to demonstrate glucose absorption pattern. The pre-treated experiment was studied in the subjects without GI tea consumption and the post-treat was the same group of subjects who consumed GI tea at 0, 15, and 30 minutes after the oral glucose load in OGTT. Peaks of glucose absorption of both experiments were compared using pair t-test. To evaluate the toxicity to human liver, GI tea (1.5 g in 150 ml water) was consumed once a day for 28 consecutive days, and the liver function tests (AST, ALT, ALP, GGT) were monitored throughout the study. The mean peak glucose concentration in the 15 minute post-treated group is significantly lower than the pre-treated group (131+-27.3 vs 145+-27.2 mg/dL; p < 0.05). Experiments using standard meal instead of glucose load gave similar results. All liver enzymes revealed no change along the study. So, GI may have potential use for suppressing glucose absorption in diabetes mellitus with no apparent acute and long-term toxicity on liver. Investigation of the underlying mechanism of the hypoglycemic effect revealed that GI extract did not increase insulin secretion in INS-1 cells and had no inhibitory effect on alpha-glucosidase. Our study also suggested that there was no association between -374 T/A and -429 T/C polymorphisms of RAGE gene and the development of neuropathy in Thais with type 2 diabetes.