Preheat oven to 425 degrees F. In a medium bowl combine the flour, oats, baking powder, and sugar substitute. After it is mixed, create a well in the center of the mixture.
In a separate bowl, combine the milk, egg, and oil. Add this mixture to the dry ingredients, and stir just until moistened. Gently fold in the blueberries and then spoon the batter into muffin pans coated with vegetable cooking spray.
Sprinkle cinnamon over the muffins, and then bake for 20 to 25 minutes, or until they are lightly browned.