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What is this research about?

Type 1 diabetes (T1DM) is a chronic disease,often affecting youth, in which the bodyproduces very little or no insulinthehormone that helps to control glucose, lipid,and protein metabolism. Poorly controlleddiabetes is one of the main causes of heartattacks, and can lead to blindness and kidneydisease. People with T1DM often experiencehigh and low levels of blood sugar. (Highlevels are called hyperglycaemia, low levelshypoglycaemia.) As a result, people withT1DM need to take insulin via injections or byan insulin infusion devise (or pump) in orderto maintain a proper balance. But it can behard for young people to do so since theirinsulin needs are always changing.

Physical activity, like exercise and sports, canpose a particular challenge to kids with T1DM.Although exercise and sports have importantbenefits, they also have an impact on bloodsugar levels. After exercising, a childs bloodsugar may be low because the child hastaken too much insulin or not eaten enoughcarbohydrates for the insulin given.

Symptoms of hypoglycemia may includetrembling, an accelerated heart rate,sweating, and increased hunger. On the otherhand, if not enough insulin is taken orbecause of elevations in stress hormones, anindividuals blood sugar may rise during some

forms of vigorous physical activity.

Thus, exercise may cause either hypo orhyperglycaemia, depending on the intensityand timing of the activity. A child may feeltired or dehydrated, or may even have blurredvision. Unfortunately, the symptoms of highand low blood sugar are often hard to detect

when a child is engaged in exercise andsports. Many of these symptoms, after all,look like the normal signs of vigorousexercise. Its important, then, for activechildren and adolescents with T1DM to keepa close eye on their blood sugar.

But the degree to which high and low bloodsugar levels affect a childs sportsperformance is unclear. Very few studieshave looked at how these levels impactphysical activity in those with T1DM.

What did the researchers do?

Researchers at York University and theHospital for Sick Children looked at how bloodsugar levels affect the physical activity ofchildren with T1DM. This was the first study

What you need to know:

Low blood sugar has a negative effect onthe athletic ability of adolescents with type1 diabetes. It also affects their ability torespond to visual stimuli.

Low blood sugar impacts athleticperformance in kids with diabetes

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that examined sports performance as it

relates to different levels of blood sugar inadolescents with type 1 diabetes. This wasalso the first study to measure non-endurancetype sport performance in people with T1DM.Children and adolescents, between the agesof 9 and 17, were recruited from the 2009York University Diabetes Sports Camp andfitted with continuous glucose monitors (GCM)for 3-5 days during which they performedvarious sports.

What did the researchers find?Low blood sugar levels decrease the ability ofchildren and adolescents with T1DM to carryout basic sports skills. Only one of the 28adolescents studied performed better with lowblood sugar than with normal blood sugar.The rest showed a decrease in their athleticperformance on average by about 20%.However, its clear that this decrease in abilityis highly individual; some children with lowblood sugar performed better than others. Incontrast to this finding, the researchers foundthat neither high blood sugar nor a prior bout

of low blood sugar significantly affects sportsskill performance.

Past research shows a similar decrease inmath performance scores, caused by lowblood sugar. As a result, the researchersdecided to look at how the kids they werestudying did in terms of cognitive processing.They found that low blood sugar impairs theability of adolescents to respond to visualstimuli including colour recognition and wordnaming.

How can you use this research?

Children with T1DM who engage in athleticactivities need to be vigilant in payingattention to their blood sugar levels. This willhelp them to maintain their health and

maximize their capacity to compete. In

addition, any obvious decrease in athleticability such as poor passing or failed serves should be a warning sign to young athleteswith diabetes to check for low blood sugar.

More research is needed on the prevention ofhypo and hyperglycaemia caused by exercisein adolescents with T1DM.

About the Researchers

Michael C. Riddell is Associate Professor inthe School of Kinesiology & Health Science at

York University and an Adjunct Professor atthe Hospital for Sick Children. Jill K. Hamiltonis a paediatric endocrinologist at the Hospitalfor Sick Children. Dylan Kelly is anundergraduate student at McMasterUniversity, funded through the NaturalSciences & Engineering Research Council ofCanada. This Research Snapshot is fromtheir article, Blood glucose levels andperformance in a sports camp for adolescentswith type 1 diabetes mellitus: A field study.mriddell@yorku.caKeywordsDiabetes, type 1 diabetes, T1DM, glucose,blood sugar, Canada

This work is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 2.5 Canada License.

Knowledge Mobilization at York

Yorks Knowledge Mobilization Unit providesservices and funding for faculty, graduate stu-dents, and community organizations seeking tomaximize the impact of academic research and

expertise on public policy, social programming,and professional practice. It is supported bySSHRC and CIHR grants, and by the Office ofthe Vice-President Research & Innovation.kmunit@yorku.cawww.researchimpact.ca

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