with my pre workout meal I dose 10 units of humalin R. It just makes more sense to have the insulin active during and after your workout instead of just post. By drinking an intra workout shake of fast acting carbs and protein, the slin peaking during the training, they go straight to your muscle. Then the slin still active post workout you get the same benefits as well.
Done on training days only, and only once a day, I don't see how this can be dangerous at all. I do this when cutting or bulking and keeps me bigger and fuller.