Type 1 Diabetes in Adolescents-Exercise Induced Hypoglycemia

Dr. Fran Cogen Health Pro

    My day-to-day meetings with my children and adolescents with diabetes revolve around the interaction of medication, nutrition, and exercise. These are the variables of which we can actually measure and have some degree of control. The variables are intricately related and serve to determine the serum glucose level. A change in one of the variables will undoubtedly have both an immediate and in many cases a delayed effect on glucose levels. Indeed, delayed hypoglycemia is one of the biggest concerns of patients, families, and healthcare providers- especially overnight. Clearly, it has been demonstrated that exercise-induced hypoglycemia may be delayed considerably.

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    A recent paper written by Metcalf, Singhvi, Tsalikian, Tansey, Zimmerman, Esliger and Janz (as directed by Anne Bartlett, fellow blogger) in Diabetes Care DOI: 10.2337/dc13-1973), Effects of Moderate-to-Vigorous Intensity Physical Activity Overnight and Next-Day Hypoglycemia in Active Adolescents with Type 1 Diabetes, sheds further light on this difficult subject.


    What was the objective of the study?


    The authors wished to examine the acute temporal associations between moderate-to-vigorous intensity physical activity and the relationship to hypoglycemia (<70 mg/dl) using continuous blood glucose monitoring.


    How was the study conducted?

    1. 19 participants with type 1 diabetes 14-20 years of age
      1. 53 percent females
      2. 47percent males
      3. Fitness was measured by indirect calorimetry
      4. Body composition was measured using air displacement plethysmography
      5. An accelerometer was always worn for 3-5 days and data was used to estimate the minutes of physical exercise/day
      6. Blood glucose levels were tracked via continuous glucose monitoring

    Based on these data, the likelihood of nighttime and next-day hypoglycemia due to moderate-to– vigorous exercise was examined (using logistic regression analysis).


    What were the results?

    1. Participants were of average fitness and accumulated 60 minutes/day of moderate-vigorous physical activity.
    2. Hypoglycemia risk was increased by 43 percent overnight and was 31 percent more likely on the following afternoon for those who accumulated 30 minutes/day more of moderate-vigorous exercise in the previous afternoon than those with less exercise (P=0.017- statistically significant)
    3. The authors also found that there is an increased time bucket 32 hours after activity in which adolescents were at continued risk of hypoglycemia.


    What may we conclude from these results?

    Based on the data above that is statistically significant (although the sample size is small), participation in moderate-vigorous exercise significantly increases the risk of the overnight and next day hypoglycemia for both sexes, independent of fitness and concurrent moderate-vigorous exercise. 


    Practical Suggestions:


    This study further confirms other evidence based studies and patient experience. It is therefore paramount to plan ahead and develop exercise strategies to avoid or reduce as much post-exercise induced hypoglycemia as possible. For those student athletes that exercise daily, adjustments must be made on those days and the following day. Changes to insulin pump basal rates should be strongly considered employing either different patterns (exercise vs. non-exercise) or temporary basal rates. Experimentation to determine the amount to decrease basal rate is important, as blood sugars will vary in the individual depending on the sport or activity. Thus, what may be effective for basketball, may not work for baseball, lacrosse or football. Developing patterns for individual sports during the different seasons is very effective. Use of a continuous glucose sensor will also be of great assistance in this endeavor.


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    For those who participate in moderate-vigorous exercise using multiple daily injections, adjustments will also need to be made and may include change in correction factors, insulin/carb ratios, and basal insulin. Keep in mind that everyone is different and what may work for one individual may not be effective for all. It is also to important to balance the high blood sugars that sometimes result from adrenalin before a game as well as the post-exercise induced hypoglycemia that may result later.  Your diabetes healthcare team can help determine the appropriate individualized strategy that will work for you!

Published On: March 17, 2014