The present invention is related to the use of an overground part of Hedychium coronarium Koenig in lowering blood glucose, increasing insulin levels and treating and/or preventing diabetes without overly reducing blood glucose in a subject i.e., not reducing blood glucose in a fasting subject. The present invention also relates to an extract and composition of the overground part of Hedychium coronarium Koenig and its use in lowering blood glucose, increasing insulin levels and treating and/or preventing diabetes.[IN-MUM-2011-00235A]