Really depends. If you are T2 diabetic - you really need to avoid carbs in general. Everyone is a bit different of course, but that is the general mantra. Full grain or not - it is still carbs, and while the fibre in full grain helps a bit - it doesn't mean you can eat the way you used to or even close. Veg - yes, again depends what kind. Meat - absolutely. My diet consists of meat and cruciferous vegetables.Go as full-grain as you possibly can and cut out white flour, rice, pasta etc as much as you can. Brown basmati rice and whole wheat or other cereals are good substitutes. Oats are good too and high in beta-glucans which are good.
At least half your plate, needs to be vegetables. Make sure your shopping basket reflects this new reality (unless you already do that of course). Fruit is good, but be careful not to over do it. Avoid juices and such.
The only way to really see this - in real time - is to use a continuous glucose monitor. Bit of an eye opener and a game changer. Again - i'm referring to T2 diabetics.