In a medium saucepan combine the sugar and water over medium heat and bring to a brisk simmer, stirring occasionally. Add the sage and blueberries and continue to cook over low heat for another 5 to 10 mintues. Remove from the heat and let stand another 10 minutes. Strain through a fine mesh sieve, pressing on the solids. Discard the solids and store in an air tight container in the refrigerator for up to 3 weeks.