The invention relates to application of compounds, which are separated from ganoderma fungi and have alpha-glucosidase inhibiting activity, to medicinal treatment and functional food health care. The alpha-glucosidase inhibiting activity of the compounds or natural or synthetic components containing one or more of the compounds is 1.6-26 times of that of acarbose. The compounds or the components containing the compounds can be prepared into a variety of solid or liquid oral preparations, or through addition of other components and auxiliary materials, compound medicines or health products are prepared and are used for treating and preventing diabetes.