It's more the fact that in the absence of enough carbs, the body also can make its glucose from both fat and protein, which caused me to query it - not that the brain needs X amount of glucose at all!
In the absence of glucose, the body closes down a good many bits before it closes the brain - I've been that hypo when I could not speak, move or see but I could still hear and think so when my colleague speaking and listening to the 999 operator relayed 'Well I think she does have a denture - but her mouth and jaw appear to be completely set and I shouldn't think we'd be able to remove them for her' - I though 'Love you, Val! Thanks' Yes, we can get her into the recovery position, and two male colleagues co-ordinated doing that with me (whist another colleague, the g/f of one of them shrieked loudly 'Don't touch her T !' and my brain thought 'Up yours too!' - and T had ignored her anyway, assisted by our Managing Director the other side of me who told the (silly cow) woman to 'Do shut up!' whilst my brain thought 'I'm glad you're here!' and then the paramedic arrived bearing glucometer and told me who he was when my brain thought Thank God for that and that he was going to test my BG as he did it, told me it reported LO so he was going to set up a glucose drip into my arm and did so, and I now understand exactly why 'ambulance people' talk to their patients constantly even when they seem to be 'out of it'.
Fascinating! - but I don't recommend finding this out that way ....... bit OTT really all in all !