But book "Willpower" mentions a lot of research where glucose did a lot positive for, well, not cognition, but for Willpower, ego depletion, and resilience.
The research on that whole area of psychology is inclusive at best, despite making a fun and compelling narrative. https://pubmed.ncbi.nlm.nih.gov/29591537/
Well, the book Willpower also does mention research experiments with description of the process, not out results. I don't know who to believe, this one paper, or theirs multiple.