Author(s): MELIN, A., LESPAGNOL, E., COMBES, A., BERTHOIN, S., RABASA-LHORET, R., SAVINA, Y., TAGOUGUI, S., BAUTIN, N., BAUDOUX, F., DESCATOIRE, A., VAMBERGUE, A., HEYMAN, E., Institution: UNIVERSITY OF LILLE, Country: FRANCE, Abstract-ID: 573

INTRODUCTION:
For adults with type 1 diabetes (T1D), evidence that high-intensity interval aerobic exercise (HIIE) prevents hypoglycaemia vs. moderate-intensity continuous exercise (CONT) remains inconsistent. Glycaemic responses may vary with exercise timing during the day or relative to the last bolused meal. In the few matched-work studies available in literature, two third (1;2;3;6) of those using an exercise performed >3h after the last bolused meal reported a protective effect of HIIE on glycemic decrease during exercise, while none of the three studies using an exercise performed <2h after the last bolus demonstrated protection (8; 9; 10). No studies used in the same design postprandial (PP) and postabsorptive (PA) exercises. Given interindividual variability, within-subject testing is needed. In addition, carbohydrate intake during exercise recovery and its confounding impact on glycaemia were almost never reported in the previous studies, while satiety may differ depending on exercise modality and intensity. This randomized crossover study compares HIIE vs. CONT in early PP and PA, while controlling diet and insulin during exercise and early/late recovery.
METHODS:
Twenty-one physical active adults with T1D using continuous glucose monitoring (CGM) completed 4 conditions: HIIE-PP, CONT-PP, HIIE-PA, CONT-PA. Cycle-ergometer sessions were work- and duration-matched: warm-up and active recovery at 20% maximal aerobic power (MAP); HIIE comprised 10×1 min at 100% MAP with 1 min passive recovery; CONT consisted of 20 min at 50% MAP. Exercise started 1.5 h and 5 h after lunch in PP and in PA, respectively. Outcomes were analysed using linear mixed-effects models or mixed-effects binary logistic regressions.
RESULTS:
Despite matched work and duration, HIIE elicited higher oxygen consumption (P=0.02), heart rate (P<0.001), lactate (P=0.014) and RPE (P<0.001) than CONT, while perceived enjoyment was comparable. Muscle blood volume variation (near-infrared spectroscopy) increased less during HIIE than CONT (P=0.04). Capillary glycemia declined faster when pre-exercise glycemia was higher (P<0.001). The decline was attenuated in PA vs. PP (e=+0.313 mg·dL⁻¹·min⁻¹, P=0.003) and in HIIE vs. CONT (e=+0.074 mg·dL⁻¹·min⁻¹, P=0.038), with a stronger HIIE protection in PA than PP (three-way interaction P=0.001; HIIE vs. CONT slope difference: +1.85 mg·dL⁻¹/25 min in PP vs. +26.92 mg·dL⁻¹/25 min in PA). During the 24h-recovery period, time spent <54 mg·dL⁻¹ was lower following HIIE vs. CONT (P=0.011), despite lower dietary glycemic load (P=0.046).
CONCLUSION:
Overall, HIIE may provide greater training efficiency (i.e., higher energy expenditure for comparable perceived enjoyment) and, when performed postabsorptively rather than postprandially, may offer stronger protection against hypoglycaemia than CONT.
(1) Jayawardene, 2017; (2) Molveau, 2025; (3) Moser, 2015; (6) Parent, 2024; (7) Da Prato, 2024 ; (8) Sarnblad, 2021; (9) Sills, 1983; (10) Tonoli, 2015.