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Carbohydrate Adjustments for Exercisers with Diabetes

What to Look for Before You Exercise

-- By Becky Hand, Licensed & Registered Dietitian
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Many people with diabetes have special needs that should be considered when planning an exercise program.

Exercise can cause your blood glucose levels to drop too much, especially if you take insulin or other glucose-lowering medications. Symptoms of hypoglycemia, or "low blood sugar," include feeling shaky, lightheaded, weak, confused, anxious, fatigued, irritable, or hungry, headache, breaking out into a clammy sweat, or even fainting.

Hypoglycemia can happen during exercise, right after exercise, or even up to 24 hours after you finish exercising. Symptoms of hypoglycemia can be mild and gradual; but it is more common that symptoms come on very quickly. By paying close attention to how you’re feeling, you can prevent problems before they put you at risk of injury.

Because of the risk of hypoglycemia, you should always check your blood glucose level before you exercise. Having a carbohydrate containing snack prior to exercising is one way to prevent exercise related hypoglycemia. Use the chart below to make the recommended adjustments, based on your glucose reading, before you exercise. Click here for a detailed, printable chart that shows single (15-gram) servings of carbohydrate-containing foods.

Adjustments Based on Blood Glucose Levels Before Exercise
 
Exercise Duration & Intensity <100 mg/dL 100-180 mg/dL 180-250 mg/dL
< 30 min. at low intensity Eat 15 g carbohydrate N/A N/A
30-60 min. at moderate intensity Eat 15 g carbohydrate 100-120: Eat 15 g carbohydrate. 121-180: N/A N/A
30-60 min. at high intensity Eat 30 g carbohydrate Eat 15 g carbohydrate N/A
> 60 minutes at moderate intensity* Eat 15 g carbohydrate per hour of activity Eat 15 g of carbohydrate per hour of activity After 1 hour of activity, eat 15 grams carbohydrate
 
 
  • Examples of low-intensity exercise: yoga, leisurely walking or biking
  • Examples of moderate-intensity exercise: vigorous walking, swimming, tennis
  • Examples of high-intensity exercise: running, Spinning, aerobics or kickboxing
  • Examples of long-duration (60+ minutes) moderate-intensity exercise:team sports, golfing, cycling or swimming
*Retest your blood glucose after each hour of activity and follow recommendations based on your reading. Contact your physician if you experience symptoms of hypoglycemia during or after exercise for 2 or more consecutive days.

For more specific information or help, talk to your health care provider. The American Diabetes Association's National Call Center also offers live advice from 8:30 a.m. to 8 p.m. EST, Monday through Friday at 1-800-DIABETES or 1-800-342-2383.

This article has been reviewed and approved by Amy Poetker, Registered Dietitian and Certified Diabetes Educator.
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About The Author

Becky Hand Becky Hand
Becky is a registered and licensed dietitian with almost 20 years of experience. Through her company, An Ounce of Prevention, she makes nutrition principles practical, easy to apply and fun. See all of Becky's articles.

Member Comments

  • FALIPY
    I have Diabetes Type 1 and I am struggling not even with my weight, but my glucose levels from high to low ! It is frustrating .... I absolutely love this article and this site as well. Tomorrow is my first day on diet, so wish me luck ;)
    - 3/24/2013 11:57:23 PM
  • This is very helpful. I do 1 hr on the elliptical every day and often feel a little shaky afterwards. Its so hard not to run for the first high-carb thing I see afterwards. Maybe carbing up a little before my workout will help. - 6/3/2012 8:32:44 PM
  • I am so excited about this info. I now know how to treat all the low BS I've been having since I have been exercising! I thought I just needed to increase proteins, but I now see that I should consume a carb before activities. My snacks are very important and I need to eat them at the times they are scheduled (my own schedule). I have a bad habit of pushing food off when I am feeling ok - getting preoccupied or busy. - 5/9/2012 2:42:43 PM
  • I hate those nasty lows. Now I know how to avoid them. Thanks! - 11/24/2011 9:02:43 PM
  • JEAN_W_1960
    Thank you for this article. My husband just started taking Metformin yesterday, and will be working out at the gym after work Thursday night. I'll pass this information on to him. He will be attending educational classes about diabetes, but you know that takes time. - 11/16/2011 11:44:25 AM
  • Wow, this has been an area of great struggle for me. After a knee replacement I use my stationary bike regularly. When I am keeping up with my exercise I have the hardest time with my eating, I get so hungry and tired in the afternoon that I blow it! I will be eating 15g of carbs before biking and seeing if my outlook for the rest of the day is improved. - 8/6/2011 9:50:03 AM
  • This chart will be very useful. - 8/2/2011 11:14:42 AM
  • Thank you so much for the printable chart! I often find the I don't really know what a serving size is! No more adjusting too much! - 7/28/2011 2:19:13 PM
  • Great article. I know I easily go low after exercise and always plan a small snack for after working out. Be very careful if you exercise at night because you could have these episodes occur at night while you are sleeping and that can be scary. I have managed to stop taking medicine and with diet and exercise I am well controlled with an A1c @ 5.6. Now if only these pesky pounds would disappear! - 7/28/2011 12:33:21 PM
  • MOM2FOURONLY
    This is a very good article. My only complaint is that the chart is useless for me as I am Canadian. We don't use the same measurements for glucose readings so I have no idea what the chart numbers mean. It would be great if you could put both the American and the Canadian equivalents on the chart. - 7/28/2011 10:00:57 AM
  • Thanks for the information! I have been aggressively working on managing my type 2 diabetes. Since March my A1c has dropped from over 11 to under 8 plus I have lost about 20 lbs. But, I have had two low Blood Sugar episodes the last few weeks. One was after a 6 mile walk so this is really timely for me!!! - 7/18/2011 6:50:23 PM
  • MISSOTIS1
    I'm new to SparkPeople. What an appropriate place for me because in High School our nickname was the Sparkplugs! Discovering new ways to exercise is a challenge I face because of my many health issues. The temptation to skip exercise is always present. The article on Beginning Exercise was very helpful to me. - 6/18/2011 3:57:33 AM
  • GIRLATPEACE46
    I am new at this Spark People team thing but a friend of mine lost 88 lbs and she looks great. I am proud of her. I've been taking meds for diabetes for the past two years and my dr thinks that I can get off the medication by my choices. WW was cut from the family budget and so was the YMCA so I am trying to get support with my fitness and weight loss goals here. I am not ready for posting pictures but I've appreciated all the articles and comments posted here. Thanks. - 4/22/2011 8:44:53 PM
  • i also have found that i bottom out when i eat allot of things with white flour in them. so i have almost completely switched to whole wheat and that has helped allot. - 3/18/2011 7:53:55 PM
  • both my parents where diabetics my mom had to be on three shoots of insulin a day plus a sliding scale.. she would bottom out often.. as a nurse i learned the term for my mom and that was fragile diabetic. one day some thing told me to check on my mom at the nursing home. it was very early and before work. i came in and found her almost ina coma she would not respond to me at all or anyone else. her sugar was below 30 and the nurse tried two different thing to get her sugar up and i said she needs the er . we went it took all day to get her sugar and then it was 250.
    my problem is since i was 30 i have had what i call weak spells and have been diagnosed as a borderline diabetic. one md told me i would not be borderline for long.. that was 19 years ago and i still am fighting with diet and exercise. only. my md now says i have metobolic syndrome and that i had to lose weight and exercise or else. my sugar was 138 not bad but i was 30 pounds overweight.
    so here i am working on it again, not wanting to end up like my mom,. but it is a very fine line because to lose weight you have to cut your calories and exercise but then you can bottom out at any time. so balance is the key.
    that you for your article cause. it will help me to regulate my blood sugar better...i tend to exercise before i eat not a good idea when i have the same issues as my mom my sugar bottoms out allot. up down up down... just me ginger - 3/18/2011 7:52:22 PM