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From Jonesborough, Tennessee, USA:

My 12-year-old daughter, 5 feet, 6 inches tall and around 150 pounds, is on a swim team and practices at least three nights a week. She began menstruating about a year ago. She is on an insulin pump and has a CGM. We struggle daily with her blood sugars. Lately, she has been having nightly highs that are resistant to insulin. These highs continue throughout the night and bolusing has no effect. At bedtime, her sugar is normal. These highs begin around midnight and last until she wakes. I have been checking her sugar about every couple of hours during the night and correcting with insulin, but her blood sugar continues to remain around 250 to 300 mg/dl [13.9 to 16.7 mmol/L]. This week, after a couple of nights of highs, I increased her basal rates during this time and she experienced several lows. The following night, she was back to the highs. Both evenings, she swam before dinner. This has been going on for about five days. She swam on the last two nights...the one where I had increased her basal rates and she experienced lows and last night where she was high. Three days a week, her practices are 1.5 hours long; the other two days, they are 1 hour long. But, she attends only three of these practice sessions on a weekly basis. She disconnects from the pump, never more than two hours, during swim practice and has around a 15 gram snack for which she does not bolus. Her sugar is usually normal at the end of practice. Yesterday, however, she did experience a low during practice, treated it, was normal at dinner and bedtime, and was high the remainder of the night. Usually, after swim practice, her sugar is relatively stable. We normally bolus as we would any other time after her practices and she is fine. She has been swimming for two years and I expected her to be low later in the night after practicing. There have been about three occasions in the last couple of months that she has had to stop practice early for lows. The highs she experienced this past Sunday night could have been a rebound from a low. She did experience a low that lasted for about an hour. We treated it about four times to get her glucose back to normal and, then, about 2 hours later, she experienced the high that lasted all night. Do such rebounds usually cause insulin resistance?

This has happened from time to time, but never for this long. I can usually attribute it to a high fat meal, but the last couple of days I have been extremely careful to limit fat at dinner to try to eliminate the highs. Could this be a growth spurt? Is this common during puberty? What can I do to try to minimize these highs?


Thank you for a very informative letter. I hope you find my responses helpful.

You did not tell us your child's overall degree of glucose control by relaying her recent and past HbA1c values. Given her use of a pump AND a continuous glucose sensor AND she exercises AND you monitor so frequently, I am going to ASSUME that her overall glycemic control is good. So, if that were the case, there would be a couple of ways you might approach this.

  1. Do nothing different than you already do. Allow her to have her higher readings in the middle-of-the-night (so long as she doesn't have ketones!) and then correct her the next morning as you would with any other high.
  2. Start to "chase" or attempt to prevent the higher readings recognizing that you might continue to fall into the hypoglycemic range that you already have.

Does puberty and a growth spurt interfere with insulin action? Yes. Of course, exercise has wonderful and sometimes difficult effects on glucose. Yes, in overall terms, exercise lowers blood glucose, sensitizes the body to insulin, and overall "by-passes" the effect of insulin. But, sometimes this lowering is rather delayed. The only way you will know how much of the higher readings relates to "rebounding" is to monitor for the lows, (your CGMS should help here) and NOT overtreat any lows.

Again, assuming she is in very good control, if she were MY patient, I would take the approach of "WOW! I am glad you exercise so much! It is so good for you and your overall diabetes management [I wish more young people with and without diabetes would exercise] and, FOR NOW, I am willing to allow you to have a bit higher readings, so long as there are no ketones (and you are not requiring to awaken in middle of night to urinate or drink) and correct the following morning." When life later likely leads to her doing less exercise, you can adjust.

Your own diabetes team may have a different approach. What have they advised you?


Original posting 28 Feb 2011
Posted to Hyperglycemia and DKA and Exercise and Sports


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Last Updated: Monday February 28, 2011 11:13:38
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