"Additionally, the summarized study did not record the timing of snack and water consumption. This is relevant because the sequence and timing of subsequent meals (or snacks), as well as the food processing and variability, can influence postmeal glucose responses." - probably a factor, hydration status is huge. This result is kind of like 'duh' though.
Hydration, activity and stress levels. Adrenal responses can pause the digestive process to conserve energy for fight or flight. Muscle use also diverts resources, stressed or not. And being dehydrated essentially concentrates everything in your blood, complicating kidney and liver function.
https://pubmed.ncbi.nlm.nih.gov/28739050/