Preheat oven to 375 degrees F. Grease cookie sheet lightly. Sift flour, baking soda, and baking powder. Work margarine and peanut butter with spoon until creamy; gradually add brown sugar replacement, continue working until light. Add granulated sugar replacement and egg; beat well. Mix in dry ingredients thoroughly. Drop by teaspoonfuls onto cookie sheet; flatten with tines of fork in a criss-cross pattern. Bake until done, 8-10 minutes. Makes 18 cookies. Nutritional information per cookie: calories 45 Diabetic Exchanges per cookie: 1/4 Bread, 1/2 Fat, 1/4 Lean Meat. ----