Check out the work of Thomas Seyfried.
He and his people have developed a press-pulse protocol that puts the patient on a ketogenic diet to deprive the cancer of sugar (the press), plus a combination of fasting (if the patient is up to it) for five days to a week before the dose of chemotherapy or radiation (the pulse). It’s a form of treatment that works quite well. Dr. Seyfried said in one recent interview that he’d prefer to eliminate the chemo and the x-rays, but that’s the standard of care.
So in Dr. Seyfried’s protocol, the fasting takes the job of really lowering glucose, making the machine unnecessary (of course, it is quite a help to carb-burners; they would not be in shape for fasting to help to the necessary degree).
As far as “dangerously low” is concerned, the concept is different for carb-burners versus ketonians. For the former, blood sugar below 70 mg/dL/3.9 mmol/L is a real problem, but for people with ketones in their blood stream, it can safely go as low as 50/2.8 or even below. There is a limit to how low, of course, because the brain apparently needs some minimum amount of glucose (though nobody knows how much), and the red blood cells need glucose to survive, becaue they lack mitochondria and therefore cannot metabolise fatty acids or ketones.