Hypoglycemia

You should know the signs of hypoglycemia (low blood sugar) such as feeling weak or dizzy, sweating more, noticing sudden changes in your heartbeat, or feeling hungry. If you experience these symptoms, stop exercising and test your blood glucose. If it is 70 or less, eat 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, test your blood glucose again to find out whether it has returned to a healthier level. Once blood glucose is stable, if it will be at least an hour before your next meal, it's a good idea to eat a snack.

To be safe when you exercise, carry something to treat hypoglycemia, such as glucose tablets or hard candy. Another good idea is to wear a medical identification bracelet or necklace (in case of emergency). Teach your exercise partners the signs of hypoglycemia and what to do about it.

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