A buckwheat extract comprising at least myo-inositol, D-chiro-inositol, a fagopyritol, one MAPK-stimulating compound, and one glucose-uptake inhibiting compound. A substantially pure glucose-uptake inhibiting compound selected from a buckwheat extract. A method for providing a glucose-uptake inhibiting extract from buckwheat seed comprising first contacting said buckwheat seed with a non-polar solvent, then contacting said buckwheat seed with a polar aprotic solvent, and then finally contacting said buckwheat seed with a third solvent. The third solvent may be a polar aprotic solvent or a polar protic solvent. The extract produced by contacting buckwheat seed with the third solvent is dried to remove the solvent therefrom. Compositions comprising dried glucose-uptake inhibiting buckwheat extracts and purified compounds therefrom.