Can physical activity cause low blood glucose?

Physical activity can cause hypoglycemia (low blood glucose) in people who take insulin or certain diabetes pills, including sulfonylureas and meglitinides. Ask your health care team whether your diabetes pills can cause hypoglycemia. Some types of diabetes pills do not.

Hypoglycemia can happen while you exercise, right afterward, or even up to a day later. It can make you feel shaky, weak, confused, irritable, hungry, or tired. You may sweat a lot or get a headache. If your blood glucose drops too low, you could pass out or have a seizure.

However, you should still be physically active. These steps can help you be prepared for hypoglycemia:

Before Exercise

• Be careful about exercising if you have skipped a recent meal. Check your blood glucose. If it's below 100, have a small snack.
  
  
• If you take insulin, ask your health care team whether you should change your dosage before you exercise.

During Exercise

• Wear your medical identification or other ID.
  
  
• Always carry food or glucose tablets so that you'll be ready to treat hypoglycemia.
  
  
• If you'll be exercising for more than an hour, check your blood glucose at regular intervals. You may need snacks before you finish.

After Exercise

• Check to see how exercise affected your blood glucose level.

Treating Hypoglycemia

If your blood glucose is 70 or lower, have one of the following right away:

• 2 or 3 glucose tablets
  
  
• 1/2 cup (4 ounces) of any fruit juice
  
  
• 1/2 cup (4 ounces) of a regular (not diet) soft drink
  
  
• 1 cup (8 ounces) of milk
  
  
• 5 or 6 pieces of hard candy
  
  
• 1 or 2 teaspoons of sugar or honey

After 15 minutes, check your blood glucose again. If it's still too low, have another serving. Repeat until your blood glucose is 70 or higher. If it will be an hour or more before your next meal, have a snack as well.

source: http://diabetes.niddk.nih.gov/dm/pubs/physical_ez/index.htm