The present invention relates to a method of preventing and/or treating diabetes type 2, also, it relates to a method of augmenting Glut4 phosphorylation and Glut4 translocation to a target cell membrane to enhance insulin signal in a signal transduction pathway; further, it relates to a simplified and inexpensive process of obtaining extract and thereafter selectively, its active n-butanol fraction and active molecule Lupinoside PA (LPA.sub.4), useful in preventing and/or treating diabetes type 2; and lastly, a pharmaceutical composition thereof.