Preheat your oven to 375 degrees F. Spray 12 muffin tin cups with cooking spray or line them with paper liners.
In a small bowl, combine the buttermilk, honey, oil, and egg whites.
In a large bowl, combine the oats, oat bran, flour, baking powder, and salt. Make a well in the center, and then add the milk mixture and the blueberries. Stir until just combined, being careful not to over mix.
Divide the batter evenly among the muffin cups and then bake for 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.