The protective effect of high-intensity interval exercise compared with continuous moderate exercise on glycemic decline is more pronounced in the postabsorptive vs. postprandial state in adults with type 1 diabetes

Engaging in physical activity while limiting apprehension related to glycemic disturbances requires a clear understanding of how exercise modality and prandial state influence glycemia in physically active adults living with type 1 diabetes. In this randomized crossover study, twenty physically active adults living with type 1 diabetes completed four experimental conditions (HIIE-PP, CONT-PP, HIIE-PA, CONT-PA). Exercise was performed on a cycle ergometer and protocols were matched for total duration and mechanical load: both included a 3-min warm-up and a 2-min active recovery at 20% maximal Aerobic Power (MAP); HIIE consisted of 10×1-min intervals at 100% MAP interspersed with 1-min passive recovery, whereas CONT comprised 20 min continuous cycling at 50% MAP. Sessions were conducted either 1.5 h after the start of lunch and the corresponding rapid-acting bolus (postprandial) or 5 h after lunch (postabsorptive). Capillary glucose and blood lactate were assessed at rest, at 10 min of exercise, immediately post-exercise, after 2 min of active recovery and after 10 min of passive recovery. Heart rate, oxygen consumption (VO₂) and vastus lateralis microvascular blood volume (total haemoglobin [THb]) were monitored throughout exercise. In addition, ratings of perceived exertion (RPE) were recorded every 5 min. Post-session enjoyment was evaluated using PACES. Glycemic excursions were assessed during exercise and up to 10 minutes post-exercise using capillary glucose measurements, and from 30 minutes to 24 hours post-exercise using continuous glucose monitoring (CGM). Carbohydrate (CHO) intake and insulin administration were carefully recorded throughout the post-exercise period. The results are presented in the paper.