It's balancing the right amount of carbs with the output of energy so any further help would be gratefully received.
Test, test and test! Write down and look for patterns , experiment with different types and amounts of carbs.
If you are going low fairly soon after starting exercise (but I think you were going high before?) Then you can eat something before starting, I tend to use about 1/2 a fairly fast acting cereal bar so thats about 12 carbs. I then drip feed dextrose (just 1 tab) about every 20-25 minutes.
The other method is to reduce insulin for meal before exercise, the disadvantage for me is that results in a higher BG than I like to be at any time and it still falls dramatically during exercise.(these hypos were the reason I was able to get a pump, now I use a pump I can just use a trickle of insulin for exercise)
If you are going low after exercise or before your next meal then again you need to eat something, I tend to use a cookie (8 carbs) bbut doctor being sensible suggests a piece of fruit.
If the lows are later,in the day then you need to reduce insulin with the meal after exercise. You need to take great care with a low gi/high fat meal or low carb meal as you will be particularly sensitive to insulin in the period after exercise. This can result in the insulin 'working' faster than the carbs and a hypo in the hour after eating. (You can get round this by injecting either after the meal or splitting the injection, some before, some an hour later)
If you are regularly exercising, then it maybe that you will need to reduce your basal insulin.
(I've written this hoping that you are using MDI, mixed insulin is a different thing entirely.)
Finally, this page on runsweet explains how many carbs are needed for various activities. It also has some good advice on things to consider when attempting to balance carbs/exercise.(Remember it is not written from a low carbing point of view,
http://www.runsweet.com/CarbsAndExercise.html