Hi howie,
When I ate the 'normal' low-fat, high-carb' diet I found that I had to drink near a whole bottle of lucozade to stop from going hypo during exercise. However, since I started low-carbing a year ago I find that I do not have to take any extra carbs if I exercise before a meal (a few hours after last taking insulin). In fact, if anything my blood sugars now rise slighly during exercise. I tend to start exercise with a bs of around 5-6 and finish with bs of 6-7. Because I do not eat much carb I do not take much insulin and therefore do not have extra insulin circulating around my body (making me go hypo).
Believe me - it took a while to get my head around this as for years I was too scared to begin any exercise without first pushing my sugars up with bottles of lucozade. But when you start to low-carb, test lots and you'll find a way.
By eating less carb (around 30-40g a day) I take much less insulin and don't have to 'chase' the insulin with lucozade anymore and as a result my bs are now a lot more stable before, during and after exercise.
Katie