High intensity interval training as a novel treatment for impaired awareness of hypoglycaemia in people with type 1 diabetes (HIT4HYPOS): a randomised parallel-group study
Question
Does 4 weeks of high-intensity interval training provide sustained improvement in counterregulatory hormone, symptom, cognitive, and hypoglycaemia-awareness responses in adults with type 1 diabetes and impaired awareness of hypoglycaemia?
Summary
This pilot randomized trial tested whether adding 4 weeks of stationary-bike HIIT to real-time continuous glucose monitoring could improve responses to low blood sugar in adults with type 1 diabetes and impaired awareness of hypoglycaemia. Compared with RT-CGM alone, RT-CGM plus HIIT improved noradrenaline, glucagon, and symptom responses during a controlled hypoglycaemia clamp, while adrenaline and cognitive-test responses did not significantly improve. The authors described the program as safe in this carefully screened, supervised clinical sample, but the study was small and disrupted by COVID-19.
Methodology
- Eighteen adults with long-duration type 1 diabetes and impaired awareness of hypoglycaemia, randomized to RT-CGM alone or RT-CGM plus HIIT.
- 18 participants.
- Stationary exercise bike.
- Work intervals: 4 x 30-second cycle sprints.
- Recovery: 2 minutes active recovery after each sprint.
- Intensity: Aim to achieve >=90% of peak HR from maximal exercise test.
- 20 minutes including 5-minute warm-up and 5-minute cool-down.
- 3 sessions per week.
- 4 weeks.
- Single-centre randomized parallel-group pilot clinical trial comparing RT-CGM alone with RT-CGM plus HIIT after a 4-week run-in period.
- Adrenaline counterregulatory response, Noradrenaline and glucagon counterregulatory responses, Hypoglycaemia symptom response, and Cognitive response during hypoglycaemia were tracked.
Outcomes
Noradrenaline response
RT-CGM plus HIIT produced a significantly greater noradrenaline response to hypoglycaemia than RT-CGM alone.
Change from baseline RT-CGM vs RT-CGM+HIIT: -988 (447) vs 514 (732) pmol/L, p = 0.02.
Glucagon response
Glucagon counterregulatory response improved after RT-CGM plus HIIT.
RT-CGM vs RT-CGM+HIIT: 1 (4) vs 16 (6) ng/L, p = 0.01.
Adrenaline response
The predefined primary adrenaline response was numerically greater after HIIT but not statistically significant.
RT-CGM vs RT-CGM+HIIT: -298 (687) vs 1130 (747) pmol/L, p = 0.11.
Symptom response
Total and autonomic symptom responses were better maintained after RT-CGM plus HIIT than after RT-CGM alone.
Mean adjusted symptomatic response was greater following RT-CGM+HIIT, p < 0.05; control total symptoms decreased 25 (3) to 20 (2), p = 0.02, while HIIT remained 27 (3) to 25 (2), p = 0.90.
Cognitive function during hypoglycaemia
No significant between-group differences were found for 4CRT or DSST during hypoglycaemia.
4CRT p = 0.41; DSST p = 0.61.
CGM hypoglycaemia exposure
Level 1 and level 2 hypoglycaemia episodes were numerically lower with HIIT but not statistically different.
Level 1: 28 (7) vs 22 (4) episodes, p = 0.45; level 2: 9 (3) vs 4 (1), p = 0.29.
Insights
- Clinical HIIT for type 1 diabetes requires glucose monitoring, individualized insulin advice, and clinical screening.
- Short stationary-bike sprint intervals may act as a strong stressor that affects hypoglycaemia counterregulation differently from moderate exercise.
- This is not directly translatable to general consumer HIIT without diabetes-specific safeguards.
Limitations
- Pilot sample of 18 analysed participants.
- COVID-19 disruption affected recruitment, retention, and delivery.
- No significant effect on the predefined primary adrenaline outcome.
- Laboratory clamp outcomes may not represent real-world hypoglycaemia fully.
- No longer-term follow-up.
Safety
- The authors state HIIT was safe in this cohort most at risk of hypoglycaemia.
- No serious adverse events were reported in the article text.
- Participants received RT-CGM, insulin-adjustment advice, HR monitoring, and clinical screening.