| Exercise and the rise in heart rate can be a signal to the liver to supply more glucose for energy and I've had some times where it seems like the liver doesn't get the message to stop pumping out extra sugar.
You might also consider not eating unless necessary until after your workouts.
For myself for the most part I try to avoid have any extra bolus insulin my system if possible.
Also, eating after your workouts is generally favored based on the principles that after exercise your body is most receptive to restocking glycogen and using protein to begin repairing muscle tissue. Eating prior to working out doesn't take advantage of that. | 
