Preheat the oven to 350 degrees.
Combine all of the donut ingredients except for the blueberries in a large mixing bowl, and whisk until evenly combined. Add the blueberries, and gently fold them into the batter with a spoon or spatula.
Spray your donut pan generously with non-stick cooking spray, and spoon the batter into the pan. This batter may be a bit thick, so you might have to spread the batter into the pan with your fingers or a spoon. Only fill it about 3/4 of the way full.
Bake for 11-13 minutes, until lightly golden and cooked through. Remove from the oven and let them cool for about 5 minutes. Flip the pan over to drop the donuts onto a metal cooling rack, and let them cool for at least 10 minutes before glazing.
In a small bowl, whisk together the lemon glaze ingredients until smooth. Once donuts have cooled, one at a time, carefully dip the top half of a donut into the lemon glaze and lightly swirl it around to coat the top. Repeat for the rest of the donuts.