Yes, diabetics can use the Nutribullet. Try some of these low-sugar recipes. https://www.nutriliving.com/recipes/diabetes.
For someone young and old, try adding ingredients that have a lot of bang for their buck like flax seeds, hemp seeds, berries, healthy fats like avocado and nuts. With someone who is older, their appetite is often lower so you want to make sure when they do eat, they are getting adequate nutrients that will help reach their goals!