Each and every diabetic responds uniquely to foods on account of the complexity of the root causes of diabetes, so it makes it very hard to know a priori what will work for you - even if it is reported to work for others. You may find that a food or combination of foods is fine for you to eat, but is not for a friend or relative. In my case, my father is also a type 2 diabetic, and what he can eat is not the same as what I can eat.
The most important thing is to not be discouraged if you hear that some particular food is a wonderful food for blood glucose control, but it doesn't work for you.
On the other hand, you may be very pleasantly surprised to find perfectly acceptable a food or foods which cause a friend or relative who is a diabetic to have problems with their blood sugar control!
I'll detail my own discoveries along this line - as I have had plenty.