In healthy people, blood sugar levels are regulated automatically by the body. Skipping meals and heavy exercise can cause a short-term drop in blood sugar, but are usually not a major cause for concern. Diabetes and hypoglycemia, however, can cause blood sugar levels to drop dangerously low. If you are prone to low blood sugar, proper preparation is the key to a successful workout.
Defining Low Blood Sugar
According to the Joslin Diabetes Center, blood sugar below 70 or 80 milligrams per deciliter is considered low, depending on the type of blood sugar meter you use. If your blood sugar is below 90 and you have symptoms of hypoglycemia, your sugar may also be considered low. However, each doctor sets target maximum and minimum blood sugar levels based on the individual patient's history and current condition. Always follow your doctor's recommendations.
Symptoms of low blood sugar, or hypoglycemia, vary from person to person. Sweating, dizziness, confusion, anxiety and weakness are common. If you feel "off" or "strange," even in the absence of specific symptoms, hypoglycemia may be to blame.
Blood Sugar and Exercise
During exercise, the body draws fuel not only from fat but also from sugar stores in the blood, muscles and liver. Because sugar found in the blood is drawn first, even short bursts of exercise can cause a temporary blood sugar drop. More intense, longer-lasting exercise depletes glycogen deposits in the liver. It can take up to 24 hours for the body to replenish these stores, leaving you at increased risk for a post-exercise blood sugar drop.
Minimizing Blood Sugar Drop
If you are on insulin or oral medications for diabetes, talk with your doctor about changing your dose during periods of increased exercise. Never make changes to your own medications without professional advice.
Check your blood sugar immediately before beginning a workout. If your blood sugar level is lower than 100, the National Diabetes Information Clearinghouse recommends having a snack before beginning your workout. Carry a fast-acting source of glucose with you, such as glucose tablets or candy. Check your blood sugar immediately after your workout and more frequently than usual for the next two to four hours. Consume 15 g of carbohydrates after your workout, adding 7 or 8 g of protein if your next scheduled meal is more than an hour away.
Treating Low Blood Sugar
Low blood sugar can quickly turn into a medical emergency. If you feel the symptoms of hypoglycemia coming on, stop exercising and check your blood sugar. If your sugar is low, consume quick-acting carbohydrates such as three glucose tablets, 4 ozs. of regular soda, a cup of milk or one tbsp. of sugar. Rest for 15 minutes and re-check your blood sugar, consuming more carbohydrates if needed. If your next scheduled meal is more than an hour away, have a regular snack after your blood sugar stabilizes.
