A composition comprising glucoraphanin for use in: reducing fasting serum glucose levels in a subject administered with said composition when compared to a subject not administered said composition； and/or preventing diabetes mellitus and/or a condition associated therewith, treating diabetes mellitus and/or a condition associated therewith, or a combination thereof in a subject； wherein the composition is intermittently administered to the subject between about 1 to about 5 times per week such that said subject is administered with a weekly dose of between about 300 to about 2500 μmoles of glucoraphanin, as well as uses of a composition prepared from a high glucosinolate broccoli and/or methods of: reducing fasting serum glucose levels in a subject having elevated fasting serum glucose levels； preventing diabetes mellitus and/or a condition associated therewith in a subject； treating a subject having diabetes mellitus and/or a condition associated therewith； or combinations thereof.
