Blood sugar level, also called blood glucose level or blood sugar concentration, is the amount of sugar in the bloodstream. Sugar, called glucose by the medical community, is the main fuel source for a body's cells. The hormone called insulin makes the glucose available for use by the cells. Too much glucose in the bloodstream is called hyperglycemia. One cause of hyperglycemia is Diabetes mellitus. A person with Diabetes does not produce enough insulin and therefore cannot control the amount of sugar in his or her bloodstream. Both long-term hyperglycemia as well as fluctuating blood sugar levels are dangerous and can cause severe side effects and shortened life span.
In some people, especially those who have high blood sugar levels before exercise, their blood sugars will rise after exercise. Normally, exercise causes blood sugar to drop, but in cases where the glucose levels are already high, the stress caused by strenuous exercise causes the liver to release excess glucose into the bloodstream.
It is very important for diabetics to consistently monitor their blood sugar levels. To make sure exercise is safe, they should test before, during, and after exercise. This will help determine when the best time of day is for exercise on an individual basis, plus it will help prevent dangerous glucose level fluctuations. The best time to test is thirty minutes before exercise and then immediately before exercise begins to make sure no major change has occurred.
The Mayo Clinic says that when the blood sugar level is between 5.6 mmol/L and 13.9 mmol/L (100 mg/dL and 250 mg/dL), exercise is safe. If the sugar level is more than 16.7 mmol/L (300 mg/dL), then levels could rise after exercise and cause an unsafe blood glucose level. In this scenario, exercise should be avoided. To prevent dangerously low levels, test every thirty minutes during extended exercise situations. If levels drop to 3.9 mmol/L (70 mg/dL) or lower, stop exercising immediately and take measures to raise blood sugar levels.
Never exercise right before bedtime, since exercise usually causes blood sugar levels to drop, and this could result in hypoglycemic levels occurring sleep. Consult your doctor to determine what type of exercise is best for your situation, and how to design an exercise program for you if you've been inactive recently.