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From Ohio, USA:

My six year old daughter is in her third year as a swimmer. She wears an insulin pump. How do you keep blood sugars within the normal range with this type of exercise? The past three weeks at practice her blood sugars were going low and did not come up for many hours later. We have never had this problem, usually just the opposite. I would treat the low and at supper on swim nights I would cover fewer carbohydrates than what she was eating so she didn't get as much insulin. She may be eating 60 grams of carbohydrates, but I would only cover 50 to 55 grams. However, it didn't seem to make a difference. Is this common in young athletes?


By far, more athletes struggle with low blood sugars after exercise than prior to or during the activity. The timeframe involved after exercise is relative because so many factors are involved which can change a situation. Everyone is different, but many individuals may need less insulin for a period after exercise. This is due to a "lag effect" where the liver and muscles cells are replacing glycogen (the stored form of glucose) -- frequently a 24-hour process. Low blood sugar several hours after exercise is often due to this "lag effect." There seems to be a higher incident in the four to six hour timeframe for many athletes, but it can be up to 24 hours. The liver and muscle cells are "stealing" glucose from the blood in order to replace the glycogen used for the activity if food is not consumed.

Using a temporary basal rate after exercise on your pump is another way to adjust for exercise. This is an easy to use feature, and handy, if you have not set up a separate exercise basal program or if you have an unplanned exercise event. It simply will reduce your basal delivery by a percentage over a period of time, for example, a 50% decrease in basal delivery for six hours.

As mentioned above, intensity, duration, and type or mode of exercise can affect how much insulin is needed over the next 24 hours. Most athletes will vary their intensity and duration due to how many minutes they play in a game, how tough the competition is and whether it is a single game or tournament over a couple of days. Many athletes have more problems controlling blood sugars with tournaments that are over a two-day period. If glycogen stores are not replaced in a timely manner (ideally within 30 minutes of a game) or adequately (15 grams of carbohydrates for every 30 to 60 minutes of activity), it is harder to keep blood sugars up for competition on the second day.

A technique to try, with the healthcare team's approval, is the rate of perceived exertion after participation. On a scale of 1 to 10 (1 is at rest and 10 is total exhaustion), rate the perceived exertion of the activity as low, moderate, or intense. A low perceived exertion of, say 3, on the scale may require a 50% reduction of basal insulin over six hours. A moderate rate of perceived exertion of 6 on the scale may necessitate a reduced basal rate of 50% over 12 hours. An intense rate of perceived exertion of 9 on the scale may need a 50% reduction over 24 hours. The only way to determine what works best is trial and error while checking blood sugars frequently. Certainly, these techniques will vary from athlete to athlete and the percentage may change (i.e., 50% to 30%) rather than duration depending on blood glucose levels.


Original posting 20 Dec 2006
Posted to Hypoglycemia and Exercise and Sports


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