Hi and welcome. What insulin has the vet prescribed Morgan and what dose?
Here is a handy chart that will aid you. It's important to aim for low carb wet/canned/raw food under 10%. Transition to low carb food slowly.
http://www.catinfo.org/docs/FoodChartPublic9-22-12.pdf
A lot of "sugar" cats here lead very healthy, happy and long lives. Your Morgan is still very young and has many lives ahead of him.
Besides a low carb diet, it is very important to home test your kitty. You can check Morgan's glucose levels with a human or pet glucometer. I prefer a human glucometer (Walmart's Relion Micro or Confirm) because the strips are cheaper. Starting out, I suggest using a 26 or 28 lancet.
Here are some handy tips and videos on getting you started on home testing. The day I learned how to home test was the day I learned CJ was hypo (glucose levels dangerously low). I avoided a trip to the emergency vet (and an expensive bill) by home testing and getting guidance here.
http://www.felinediabetes.com/FDMB/threads/testing-and-shooting-tips.85113/
http://www.felinediabetes.com/FDMB/threads/hometesting-links-and-tips.287/
Giving insulin does not hurt the cat. Neither does home testing (poking the ears).
When home testing/poking the ears, aim for the "sweet spot", the area between the vein and outer edge of the ear.
Just gently pull up an area at the nape or anywhere skin can be pulled up to give insulin. The injection doesn't hurt the cat. Home testing/poking doesn't hurt the cat either because cats have few nerve receptors in their ears, hence they don't feel pain. Get your kitty used to you touching her ears by massaging them. Reward with praises and low carb treats. Then graduate to poking with a lancet. CJ used to run from me but now she sits and waits to be poked!