Emiliano,

See this quote:

"It is counterintuitive, but the harder you exercise the more insulin  
your body needs to deal with the increased amount of glucose being  
released for energy. Often by exercising at a less strenuous pace, can  
cause BG to decrease with exercise again."

I am not certain this is bad and am a big fan of short, intense  
exercise.   Are you in ketosis?

Jim