I don't know what is suitable for a 'diabetic' but I say real food also. In fact, enough real food(in your lifestyle, not just for running) and you just may stop calling yourself a 'diabetic' some day. Look into vegan also. I will have to try the avocado for long runs. It is my favorite daily food but I never thought to try it for running.
On a side note, you might want to refer to yourself as someone with a diabetic condition rather than label yourself a diabetic. The medical industry has trained us well with their labels. It is good for business. There are many alternatives for many conditions but the industry does what it can to protect its profits.