Had prediabetes. is exercising 5 hours per week any better than 2.5 hours at preventing type 2 diabetes when both results in same # of fat lbs. lost?

Twice as good: Twice the exercise should burn off twice the weight, assuming your doing the same intensity of exercise. You need to combine it with food restriction of you're going to have any success.

Yes, more exercise.: Yes, greater amounts of aerobic exercise will help the lean muscles take up and use more sugar and thus lower the blood sugar levels.