medwireNews: Findings from the HIT4HYPOS trial suggest that a high-intensity exercise program may improve hormonal and symptomatic responses to hypoglycemia among people with type 1 diabetes and impaired awareness of hypoglycemia (IAH).
Outlining the background to the study at the 58th EASD Annual Meeting in Stockholm, Sweden, Catriona Farrell (Ninewells Hospital, Dundee, UK) said that “the most important risk factor for IAH is prior exposure to hypoglycemia itself,” suggesting that habituation (ie, a reduction in response to a stimulus as a result of prolonged exposure) could be an appropriate target for intervention.
Farrell et al hypothesized that dishabituation (ie, presentation of another stimulus to recover the habituated response) through a high-intensity exercise program could restore hypoglycemia awareness in people with type 1 diabetes, and initial research from the team indicated that this hypothesis warranted further evaluation.
The present study enrolled 18 participants with a median type 1 diabetes duration of 27 years who had either IAH or evidence of recurrent hypoglycemia on flash or continuous glucose monitoring (CGM).
After a 4-week run-in period for insulin optimization, participants were randomly assigned to take part in the 4-week exercise program – comprising three cycling sessions per week to reach an intensity corresponding to at least 90% peak heart rate – alongside real-time (rt)CGM, or to receive rtCGM alone. They underwent a 90-minute hyperinsulinemic hypoglycemic clamp at 2.5 mmol/L, with measurement of hormonal counter-regulatory responses, before and after the intervention period.
Farrell said that after taking part in the intervention, participants in the exercise group experienced a significantly greater increase in glucagon levels during hypoglycemia compared with those in the control arm, with average increases of 16.2 versus 0.9 ng/L.
For the hormonal responses, the presenter said there was a “slight increase” in the epinephrine response to hypoglycemia in the exercise group, but “little difference” with hypoglycemia in the control arm. Norepinephrine levels were maintained during hypoglycemia in the exercise group, compared with a significant decrease in the control group.
In line with these findings, analysis of symptom awareness as measured by Edinburgh Hypoglycemia Symptom scores indicated “preservation of hypoglycemia awareness in participants that had undergone high intensity exercise,” compared with “a significant reduction in symptom awareness in the control group,” reported Farrell.
She noted that the mechanisms underlying benefits of high-intensity exercise for restoring hypoglycemia awareness are unknown, but suggested that they could involve reaction of the autonomic nervous system, heightened sensitivity of adrenergic receptors, or increased central nervous system glucagon release.
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