Blood glucose levels do not reach zero even during extreme starvation, suggesting a persistent requirement for glucose.

“So glucose remember really goes away. What's changing is the consumption by the neuron which goes from, at the initial state, being about a 100% glucose...of course, I don't think they were measuring lactate then so we don't actually... [Rhonda]: Were they looking at neuron or just brain? Was it astrocytes or neuron... [Peter]: They were probably just looking at brain. Yeah. But it would fall to maybe 40% or 50%, the rest of it being made up by the combination of the ketones. And it's interesting that they never went to zero, right? So even to your last day of life, if you're being starved to death, you still have glucose in your blood.”