An interesting point.
I've had a quick go at tracking this down, but not found any immediate references, but some that advise eating gluten if you can (that is, you are not intolerant) . I think that this is because gluten is a protein and associated with fibre which is supposed to be good for you. I take this to mean that if you are eating grains, don't eat gluten free unless you absolutely have to.
Some studies suggest that going gluten free may increase your risk of developing T2 - again I assume that this may be because the carbohydrates are more easily absorbed, which would tie in with them not staying in your blood stream for as long.
With regards to carbohydrates, gluten free products (that is, bread and other grain products without gluten) are still carbohydrates. As far as I know if you avoid grains then you should be gluten free and a lot of diabetics avoid grain products to keep the carbohydrates down.
So, sympathy with your gluten intolerance which can make life very difficult; my SIL is coeliac.
However I still think that the toast and sandwiches may not be the best thing to eat as a diabetic.
I know my SIL is fine with potatoes and mainly has to avoid bread when eating out (although there can be wheat hidden in all sorts of things). Looking it up, there seems to be no gluten in corn (maize) or rice. To my mind if you are T2 diabetic and struggling to keep your BG under control these are things you can eat as a coeliac but perhaps not things you should eat as a T2.
We can only suggest what might be good or bad. Your call on what diet suits you best.
My current prejudices are that it is better not to eat bread at all than to eat gluten free. Step away from the wheat.
Step away from the carbohydrates.