Impaired autonomic function after exercise observed among healthy teens with type 1 diabetes
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A small cohort of healthy adolescents with type 1 diabetes showed signs of altered energy metabolism and cardiovascular autonomic regulation after an exercise test compared with peers of similar age and aerobic fitness level, despite exhibiting normal acute cardiometabolic responses, according to findings from a pilot study published in Pediatric Diabetes.
“When the participants performed a bout of exercise, those with type 1 diabetes demonstrated fairly similar responses compared with controls for the autonomic, CV and metabolic variables that we measured,” Kevin R. Short, PhD, FACSM, an associate professor of pediatrics and the CHF Choctaw Nation Chair in Pediatric Endocrinology and Diabetes at the University of Oklahoma Health Sciences Center, told Healio. “So, there are some signs that diabetes pathology has begun in these young people, though there are no impairments in exercise function.”
Short and colleagues measured short-term effects of a high-intensity aerobic interval exercise session on CV and metabolic variables among 15 normal-weight adolescents with type 1 diabetes (six girls; 11 using insulin pump therapy) and 28 adolescents without diabetes (controls; 14 girls). All participants performed a high-intensity aerobic interval protocol on a treadmill for 38 minutes. Protocol consisted of a 5-minute warm-up, followed by four 4-minute segments that elicited 90% of maximal heart rate, separated by 3-minute recovery segments at a workload eliciting 65% of maximal heart rate. Researchers assessed energy expenditure, heart rate variability, arterial compliance and blood pressure before exercise at three points up to 105 minutes after exercise.
Researchers found that participants with type 1 diabetes and controls had similar cardiorespiratory fitness and accelerometer-measured physical activity. Those with type 1 diabetes had higher energy expenditure and fat oxidation throughout the trial; however, any changes measured after exercise changes were similar between groups.
“Within the control group, energy expenditure was 11%, 2% and 3% higher than baseline at the three post-exercise measurements,” the researchers wrote. “For the type 1 diabetes group, energy expenditure was 5% higher at 20 minutes post-exercise (P < .001) but was not different at the final two measurement times.”
Heart rate variability “transiently declined” after exercise for both groups, according to researchers; however, participants with type 1 diabetes had lower heart rate variability at baseline.
Among the measures of arterial compliance, researchers found that the augmentation index declined after exercise for those with type 1 diabetes. Carotid-femoral pulse wave velocity and large artery elastic index were unchanged. Central and brachial BP were stable throughout the trial for both groups until 105 minutes after exercise, when researchers observed a 2% to 3% increase above baseline for those with type 1 diabetes.
“We have to be cautious about clinical claims, since this is a small study with a single exercise session,” Short said. “As noted above, the finding that young people with type 1 diabetes had signs of autonomic and metabolic changes is a concern. We don’t know the mechanisms yet, and we don’t know how much can be prevented or reversed if, for example, the participants were able to maintain tighter control of their blood glucose, but it is something we hope to explore.”
Short said studies that use exercise or improved glycemic control strategies would be valuable to determine how much of these cardiometabolic changes are preventable or reversible.
“We need that information to advise patients about the most effective strategies to preserve their health and function,” Short said. – by Regina Schaffer
For more information:
Kevin R. Short, PhD, FACSM, can be reached at the Department of Pediatrics, Section of Diabetes and Endocrinology, University of Oklahoma Health Sciences Center, 1200 Children’s Ave., Suite 4D, Oklahoma City, OK 73104; email: kevin-short@ouhsc.edu. Twitter: @Kevin_R_Short.
Disclosures: The authors report no relevant financial disclosures.
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