By: Anne Blocker
Safety first: Remember to check with your healthcare team before starting any new exercise program.
Each person’s blood glucose responds differently to activity. A key part of diabetes self-management is learning to adjust food and/or medications accordingly.
Insulin and insulin-stimulating medications (including glyburide, Glucotrol, Glucovance, Amaryl, Prandin, Starlix, etc.) lower blood glucose levels. Exercise also lowers blood glucose levels. Carbohydrate foods increase blood glucose levels.
If you manage your diabetes with diet and activity alone, you probably won’t need a snack before or after exercise. However, if you are going on a day-long excursion, you might be hungrier than usual. Conversely, if you take insulin or an insulin-stimulating medication, if you are exercising in hot weather, or if your fitness level is low, you may need to eat foods with extra carbohydrates.
Test, Test, Test
Test your blood glucose before and after activity. When exercising for more than an hour, test each hour. Keeping good records of your activity and blood glucose will help you predict your body’s response to activity in the future.
If your blood glucose level is below 100, eat a snack before starting exercise.
If your blood glucose is above 250 (fasting or pre-meal), don’t exercise. Exercising when blood glucose is high can make it go even higher. Wait until the glucose level comes down. (If you have type 1 diabetes, check for ketones in your urine. You may need to ask your healthcare provider about taking more insulin.)
Activity, too much insulin or too little food can all cause hypoglycemia. If your blood glucose gets low during exercise, stop and treat the low blood glucose. Dizziness, sweaty skin, shakiness, hunger or irritability are early warning signs.
Test your blood glucose. If it is less than 50 mg/dl, eat 20 grams of carbohydrate; if it is less than 70 mg/dl, eat 15 grams of carbohydrate. Test again in 15 minutes. If your glucose is still low, eat another 15 or 20 grams of carbohydrate and retest in 15 minutes.
Make sure you drink plenty of water before, during and after exercise. Dehydration can happen quickly in warm weather and can cause acute illness.
The Lasting Effects of Exercise
The blood glucose-lowering effects of exercise can continue for hours after you’ve stopped exercising. Test your blood glucose each hour after exercise for the first two to three hours. You may need to add a snack or reduce insulin or medication if your blood glucose levels are too low.
Over time, exercise can improve insulin resistance and result in lower blood glucose. Consult your physician about using less medication if you notice this trend.
Enjoy the opportunities the warm weather offers for outdoor fun and exercise. Remember, each person’s response to physical activity is different. Try different activities and food combinations, and keep good records to learn how to best manage your blood glucose as you engage in your favorite summertime activities.
Q: How can I be safe when exercising?
Keep the following items with you when you are exercising:
- Identification, medical ID and emergency contact information
- Source of carbohydrate: at least three 15-gram choices (juice, fruit roll-up, glucose tablets, etc.)
- Water bottle
- Glucose meter, test strips, lancets
- Cell phone, phone card or change to make a phone call
- Fanny pack for carrying your supplies