Why can't a patient eat carbs before a PET scan?

My guess is that they are trying to clear the body of natural sugars.

For a PET scan, they inject you with radioactive sugar. Tumors consume sugars up to 30x faster than healthy tissue.

@raum-That makes sense. Thanks for your answer :)

According to the Cancer Survivors Network For the PET scan they feed you some radioactive-tagged sugar. The idea is that cells that metabolize at a faster rate (such as cancer cells but also recent healing surgery sites) will take more in and thus “light up”. If you load up those cells ahead of time they may not take as much and would not light up. Prohibiting the exercise may be so that you don’t injure a muscle or area of the body as that could make that area light up as well.

A patient pointed out that the ONLY thing worse than a “false positive” result is receiving a “false negative” result!!! That makes sense to me; but being a carbaholic, I think I’d find it difficult to do!!!

@LadyMarissa -Thank you! This also explains it well.

@lucillelucillelucille Diabetics can eat proteins, it’s the amounts of carbs and sugars they have to monitor.

@janbb -Yes.They’d also require carbs if they are taking meds for it.( I am type 1 diabetic and am familiar)
What I wanted to know was why they don’t want a patient to eat carbs beforehand.I did get that answer.
If the patient is diabetic, how do they handle the possibility of a low blood sugar while in the midst of this test?
Do they instruct the patient to forego their meds beforehand and schedule the test earlier before a rise in blood sugar? (Another thing I wondered but didn’t ask)

According to the Gwinett Medical Center near Atlanta, GA
As a general rule, all patients should fast and have a blood sugar level between 70 – 200. If your blood sugar level is not within this range, we cannot do the scan and we will have to reschedule your appointment. Do not allow your blood sugar to drop below 70.

Other sites said the patient should get specific advice from their doctor as how best to handle the fast and insulin before the scans.

@SEkA-Thanks for the answer and yes, specific advice is best.