I never eat carbs even before working out which can make it hard work sometimes!!
I was told by my DN to do weights first (as they make your sugar go up) and then cardio (to bring it down).
You could try a little insulin before hand if you are really going to hit the weights, but remember to keep testing just in case!!
It'll also take your body quite a while to adjust to low carbs. I read somewhere It takes between 2-6 weeks, so you may find your needs change a bit as your body gets used to it.