Exercise is in my opinion a secondary modality for managing diabetes and health in general. I love exercise and do use this to top off my Ketovore dietary regime almost everyday. I have over trained in the past and pushed too much. Once a baseline of fitness has been built up, maybe by walking, I would recommend a split between resistance, short high intensity and flexibility.
It is not possible to out exercise a "bad" diet, as even athletes can and have developed pre and full diabetes. Diet is the key, I now see exercise as treating my body.