My path with a diabetic child is similar to MaryEllen2u's. Daughter diagnosed at age 4. Diagnosis day is still burned in my brain, but we've all learned lots since then - 1988. I immediately took a nutrition class from the continueing ed. dept of our school district that was geared to being heart healthy.
But I remember some of our favorite snack items were easy to make: frozen grapes. banana popsicles (half a banana on a stick rolled in nuts, grapenuts, or a little dip of melted chocolate chips) frozen pineapple tidbits. It made a fruit exchange "dessert-friendly". Sugar-free jello and popsicles were a bonus. If other kids had candy - sugar free gum was easy enough for other parents to give as an equal treat.
Since she was the oldest, our other two grew up with great eating habits too. As we travelled, we always carried our own treats - no concession stands for us. The 3 meals and 3 snacks a day make a lot sense.
Yes, she did acquire an insulin pump when she was 15, and she loves it. Yes, she went away to college. Yes, she worked in a research lab trying to find a cure for Type 1 diabetes at the university. Yes, she graduated and is going on for more schooling with her biology degree. She's 28 now and has helped many diabetics as a pharmacy tech.
Diabetes is a different way of life, but we've found that she matured faster than her classmates and had to depend on herself for safety and for all the other choices young adults have to make.
I've got a few other recipes to share if your great niece is interested. Diabetic eating is healthy eating.