There is much concern about the dramatic increase in the population of type 2 diabetes patients. Both the recent prevalence rate and the estimated increase in incidence have become public health problems and create a serious burden on society. In order to identify an individual at increased risk of developing type 2 diabetes, the concept of impaired fasting glucose (IFG) has been introduced by the American Diabetes Association [1]. Individuals with IFG have fasting plasma glucose levels between 5.6 mmol/L and 6.9 mmol/L [2]. In addition to being more likely to develop diabetes in the near future, these people are at greater risk for cardiovascular disease [3,4]. Therefore, effective approaches to control blood glucose levels are urgently needed. Previous largescale studies have demonstrated that lifestyle intervention is the best way to achieve this goal [5e7]. Pharmacotherapy is also used to manage individuals with IFG. Paradoxically, medications used to control blood glucose often cause metabolic side effects such as weight gain [8,9]. Thus, the development of alternative therapies is of paramount importance, and in this context, herbal extracts are among the most prom