It might be dangerous to exercise if your blood sugar level is over 250 mg/dL. Both type 1 and type 2 diabetics can benefit from exercise, which may eventually lower the average blood sugar. If your diabetes is severe or hard to control, you will need to take special precautions before you exercise. Check with your doctor before starting or changing your exercise program. This is important for everyone and essential for diabetics.
Glucose in Non-Diabetics
In a healthy non-diabetic person, the sugar, called glucose, needed for exercise first comes from the bloodstream. Insulin is released as needed from the pancreas to allow glucose to enter the cells. When there is not enough glucose in the blood, your liver releases more, which then carries it to the cells. If your liver runs out of glucose, your body will temporarily use fatty tissue for a source of energy. Your blood sugar will be lower than when you started exercising.
Type 1 Diabetes
If you have type 1 diabetes, your pancreas does not produce enough insulin. You will have to take insulin by injection in order to allow the passage of glucose into the cells. In response to exercise or stress without enough insulin, your liver will allow still more glucose to be released and the blood glucose can become even higher. Your cells, lacking insulin, are still without the glucose they need. Your body will begin to break down fat to supply energy. This is called ketosis. In a diabetic, it can progress to ketoacidosis and lead to coma and death if not treated immediately.
Type 2 Diabetes
In type 2 diabetes, there either is not enough insulin produced, the cells resist insulin, or both. Some glucose does enter the cells, however. Most people with type 2 diabetes do not progress to ketoacidosis. Those who do must be as cautious with exercise and stress.
Exercise can greatly benefit type 2 diabetics. It can reduce the amount of medication you require and, in some cases, eliminate the need for it. This is in addition to careful diet, of course.
Play it Safe
As advised by Johns Hopkins Medical, test your blood sugar half an hour before you exercise and again right before you start. If your blood sugar is 250 mg/dL or more and you have type 1 diabetes or are prone to ketosis, check your urine for ketones before you exercise. If your ketones are in the mid to high range, delay your exercise. If your blood sugar is 300 or more, do not exercise regardless of the type of diabetes you have. Wait until it is in the safe range of between 100 mg/dL and 250 mg/dL.
References
- Johns Hopkins Medical Health Alerts: Diabetes and Exercise -- Keeping Your Blood Glucose Levels in Check; Feb. 2006
- MayoClinic.com: Diabetes; Causes; Mayo Clinic Staff; March 2011
- MayoClinic.com: Diabetes; Stress, illness and high blood sugar; Nancy Klobassa Davidson, R.N., and Peggy Moreland, R.N.; Jan. 2009
- MayoClinic.com: Diabetes; Diabetic Ketoacidosis; Mayo Clinic Staff; May 2010
- "Archives of Internal Medicine"; Diabetic Ketoacidosis in Type 1 and Type 2 Diabetes Mellitus: Clinical and Biochemical Differences; Newton and Raskin; Sept. 2004
