Exercise makes insulin work harder. Your blood glucose may drop more than usual when you take your normal insulin dose. Exercise can make insulin go to work faster, too.
On the other hand, if you have type 1 diabetes and have too little insulin available, hard exercise sessions can raise your blood glucose. Hard exercise can signal your liver to start breaking down glycogen into glucose. Hard exercise means whatever is difficult for you. Remember to check for ketones whenever your blood glucose levels are too high (see tip 19).
If you take insulin or diabetes pills to control your blood glucose levels, you need to plan your exercise and diabetes care to avoid levels that are too low or too high.