Greetings mate! your question is very good.
The A.D.A. recommends a "mediterranean diet" My personal recommendation is the following, a diabetic patient can eat anything; as long as you respect the necessary portions in the day. You should base your food more on proteins than carbohydrates. After all, the body needs energy, that energy that is obtained from food (glucose); For the proper functioning of our body, the brain needs glucose to function, just as hyperglycemia is dangerous, "hypoglycemia" is also dangerous.
A hypothetical example, if you are given a portion of cake, you can eat half, and save the other half for later, thus regulating your dietary rhythm a bit.
I hope I was able to help you with this answer! a hug and thanks for commenting.