Our interest in the isolation and identification of antidiabetic compounds from natural sources initiated our investigation of banaba extracts with 3T3-L1 adipocytes as a cell model and a radioactive glucose uptake assay as a screening method for the identification of potential antidiabetic compounds. In our study, we confirmed that the water and methanol extracts of banaba leaves exhibit glucose transport stimulatory activity (28) . In addition, we showed that the activity induced by the extract had a concentration-activity profile similar to that of insulin, suggesting that the activity of banaba extract (BE) might be triggered via an insulin-like mechanism (28) . Furthermore, we demonstrated that the same BE also inhibits adipocyte differentiation (28) . 3T3-L1 preadipocytes treated with methylisobutylxanthine, dexamethasone, and insulin (MDI) and BE did not differentiate into adipocytes as they normally do under the sole influence of MDI. This result indicated that BE inhibits the adipocyte differentiation activity induced by MDI. Unlike the glucose transport stimulation, the anti-differentiation activity is anti-insulin like, since insulin plays an important role in adipocyte differentiation and is a component of MDI ('I' in MDI stands for Insulin). Thus, BE differs from insulin in that it is anti-adipogenic whereas insulin is adipogenic, which is considered to be a negative side effect of insulin.