A method for regulating blood glucose level is provided. The method comprises administering to a subject in need an effective amount of at least one of poricoic acid A and poricoic acid B, wherein at least one of poricoic acid A and poricoic acid B can be used in the form of a plant extract, and wherein in the plant extract, poricoic acid A and poricoic acid B are present in a total amount of at least 30 wt %, based on the total weight of the plant extract.