From the known studies, we conclude that tannin molecules are responsible for the insulin-like glucose transport stimulatory activity of the banaba extract. Gallotannins such as PGG appear to be more potent and efficacious than ellagitanins such as Lagerstroemin in IR binding, IR activation and glucose transport induction. Corosolic acid does not possess any insulin-like glucose transport stimulatory activity. If its antidiabetic activity can be confirmed, it is likely to be induced via a noninsulin like, indirect mechanism. Although tannins were identified as the effective component for the insulin like glucose transport inducing activity in banaba extract, the most effective tannin molecule in the extract has not been identified. A well designed bioassay (glucose uptake assay) guided isolation should be able to complete this task.