The present invention relates to a pharmaceutical composition for preventing or treating diabetes or dementia, comprising centipede grass (Eremochloa ophiuroides) extracts as an active ingredient. It has been identified from animal tests that the centipede grass extracts, fractions thereof, and active fractions separated from the said fractions effectively regulate blood glucose levels, and inhibit the activity of amyloid-β(Aβ) which is involved in the formation of amyloid plaques that might cause dementia. Thus, the extracts, the fractions thereof, and the active fractions separated from the said fractions can be effectively used in a composition for preventing and treating diabetes or dementia, in a functional food for preventing or improving diabetes or dementia, and in a pharmaceutical composition or health food for blood glucose regulation.
