Dose-Dependent Suppression of Postprandial Hyperglycemia and Improvement of Blood Glucose Parameters by Salacia chinensis Extract: Two Randomized, Double-Blind, Placebo-Controlled Studies

The number of diabetes mellitus and borderline diabetes cases is increasing and poses a serious problem worldwide. Plants of the genus Salacia are known to have α-glucosidase inhibitory activity and to lower postprandial hyperglycemia. Two randomized, double-blind, placebo-controlled clinical trials were conducted to evaluate the efficacy of Salacia chinensis extract. Study 1 was a single-dose crossover study of 150, 300, or 600 mg of Salacia extract or placebo to determine the dose dependency of the effect on postprandial hyperglycemia. The duration of the washout period between each experimental day was a minimum of 6 days. Study 2 was a 12-week, multiple-dose, parallel-group study to evaluate the effects of 600 mg three times per day of Salacia extract on blood glucose parameters. In Study 1, Salacia induced significant dose-dependent suppression of postprandial blood glucose, insulin, and their incremental area under the curve values. The dose of 600 mg appeared to have the most significant effect. In Study 2, Salacia significantly improved several blood glucose-related parameters, such as hemoglobin A1c, and glucose tolerance after glucose challenge. These results suggest that S. chinensis extract may have beneficial effects in patients with diabetes.