Pete, this recipe uses only 1/4 cup brown sugar. Splenda has a brown sugar version. I have not used the brown sugar Splenda, but it might be worth a try. If your friend is a diabetic it also is important to use less refined flours so using whole wheat in the recipe also will help with a person's sugar levels.
Whole Wheat Blueberry Muffins
Nonstick cooking spray
1 cup whole wheat flour
¾ cup all-purpose flour
¼ cup firmly packed light brown sugar
1 Tbsp. plus 1 tsp. baking powder
1 tsp. ground cinnamon
½ tsp. ground allspice
1 cup fat free buttermilk
2 Tbsp. canola oil
2 Tbsp. unsweetened applesauce
1 egg, lightly beaten
1 cup fresh or frozen blueberries
Preheat oven to 400 degrees. Lightly spray muffin tin with cooking spay. In large bowl, combine flours, brown sugar, baking powder, cinnamon and allspice. In another bowl, whisk together buttermilk, oil, applesauce and egg. Make well in center of dry ingredients. Pour in buttermilk mixture, stirring until just combined (do not overmix). Stir in blueberries. Spoon batter evenly into prepared muffin cups. Bake until tops are golden, 20-25 minutes. Transfer pan to wire rack to cool slightly. Transfer muffins to cooling rack. Serve warm.