Looking for one sugar-free dessert item [San Francisco]
Why not make a Paleo dessert. An easy one is take a banana break it into two inch pieces and freeze. Once frozen put in the blender until creamy and refreeze. Remove from the freezer as you would ice cream to soften before serving. You could put chopped nuts on top and or fresh berries. Your pie eating guests will probably want some so make plenty!
Have you talked to your guest? There are different types of diabetics, and they all have different attitudes towards desserts. Many would rather have a small amount of the "real" dessert than a sugar-free dessert and many count total carbs (rather than just sugar), which means that a cake with no sugar really isn't much different.