A level Chemistry Fuel cell help

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0038436#:~:text=We%20have%20developed%20an%20implantable,and%20up%20to%20peak%20power.&text=The%20fuel%20reactions%20are%20mediated,of%20an%20activated%20platinum%20anode.
From this article,
glucose is not completely oxidized and the theoretical maximum rate of electron transfer from
glucose oxidation is not achieved in abiotically catalyzed glucose fuel cells.
Instead, glucose is principally oxidized to gluconic acid
Anode: C6H12O6 + H2O --> C6H12O7 (gluconic acid) + 2H+ + 2e-
Cathode : O2 + 4H+ + 4e- --> 2H2O
Overall : 2C6H12O6 + O2 --> 2C6H12O7

apologies but... shouldn't the glucose produce carbon dioxide and hydrogen ions on the anode rather than gluconic acid?

Don't need to apologize because I also need to learn. As the scientific articles said, they found the glucose is not completely oxidized to carbon dioxide and usually oxidized to gluconic acid. Of course, I don't know whether it is in A level because I google relevant issues in A level but cannot be found. Thus, I still need open-minded and to learn and you tell me more about the source of the question and its relevance to the GCE A level.