Like "I found this online. http://www.healthguideinfo.com/diabetes-nutrition-exercise/p118153/ Here is just a bit of the article: Fight-or-Flight Response Why does blood sugar spike after exercising? For all of its health value, the body interprets exercise as stress. You are putting forth a greater effort during your workouts, causing a depletion of circulating blood sugar and its reserves found in your muscles and liver. You may be exercising hard enough to elevate your heart rate. These effects are caused by the release of epinephrine or adrenaline. This hormone is associated with the fight-or-flight response. It is a survival instinct with the purpose of enhancing your ability to respond to some type of stress or threat. A spike in blood sugar is not uncommon during other types of stressful events such as surgery. Another effect of epinephrine release in an increase in sugar metabolism. This response may explain the blood sugar spike after exercising. While that may appear to be harmful for a diabetic, a 2009 study by the University of Missouri argues that the body needs stress like exercise because stress is part of its evolutionary history. Researchers explain that the absence of stress can actually be the cause of harmful physiological changes. In the long run, exercise will increase your insulin sensitivity so that your body can respond more appropriately to changes in blood sugar. As a precaution, you should plan on having a small snack prior to exercise to help maintain stable blood sugar levels. The spike in blood sugar following exercise may be accompanied by a subsequent crash for which you need to be prepared. With proper blood glucose monitoring and control, you can exercise safely. I hope you find this helpful, Mary"