# 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 PMID: 38010533 Journal: Diabetologia Published: 2024 Feb Authors: Farrell CM, McNeilly AD, Hapca S, Fournier PA, Jones TW, Facchinetti A, Cappon G, West DJ, McCrimmon RJ ## 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. ## Population - Eighteen adults with long-duration type 1 diabetes and impaired awareness of hypoglycaemia, randomized to RT-CGM alone or RT-CGM plus HIIT. - Sample size: 18 - Age: 18-55 years eligible - Sex: 9 men and 9 women - Health status: Type 1 diabetes for at least 5 years with impaired awareness of hypoglycaemia and/or recurrent hypoglycaemia. ## Methodology - Single-centre randomized parallel-group pilot clinical trial comparing RT-CGM alone with RT-CGM plus HIIT after a 4-week run-in period. - 4-week run-in plus 4-week intervention, with baseline and post-intervention hypoglycaemic clamp visits. - Clinical Research Centre, Ninewells Hospital and Medical School, Dundee, UK; HIIT was delivered on stationary exercise bikes with heart-rate monitoring, including home bike provision after COVID-19 amendments. - Randomized and controlled study design. ## Protocol - RT-CGM plus HIIT. - Modality: Stationary exercise bike. - Work intervals: 4 x 30-second cycle sprints. - Recovery: 2 minutes active recovery after each sprint. - Sets or repetitions: 4 sprints per 20-minute session. - Intensity: Aim to achieve >=90% of peak HR from maximal exercise test. - Session duration: 20 minutes including 5-minute warm-up and 5-minute cool-down. - Frequency: 3 sessions per week. - Program length: 4 weeks. - Progression: None reported. - RT-CGM alone. - Modality: Continuous glucose monitoring and clinical advice without HIIT. - Frequency: Weekly contact/visits during intervention. - Program length: 4 weeks. ## Outcomes ### Noradrenaline response Status: improved 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 Status: improved 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 Status: no clear change 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 Status: improved 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 Status: no clear change No significant between-group differences were found for 4CRT or DSST during hypoglycaemia. 4CRT p = 0.41; DSST p = 0.61. ### CGM hypoglycaemia exposure Status: no clear change 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. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/38010533/) (pubmed) - [DOI](https://doi.org/10.1007/s00125-023-06051-x) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10789679/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.