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Date of last update: 10/17/2017.

Forum Name: Diabetes

Question: 72 hour fast!

 jen77 - Sun Jun 03, 2007 4:49 am

Hi i was wondering what the 72 hour supervised fast is used to determined? Also what does insulin, cpeptide and ketone levels used to determine?
 Dr. Chan Lowe - Wed Jun 13, 2007 6:51 pm

User avatar There may be several reasons to undergo a fast. During these times, the body's ability to regulate blood sugar is tested since there is not an incoming source of blood sugar.

A normal response to low blood sugar would be for insulin levels to go down and counter-insulin hormones such as glucagon to increase. This response also shifts the body into "fuel making" mode. Ketones are one such alternative energy source for the body (other than glucose).

If the blood sugar goes abnormally low it may be because there is too much insulin or too little counter hormones. When the blood sugar is low, insulin levels can be measured. C-Peptide is an indirect way of measuring insulin levels. C-peptide is created when the preinsulin molecule is cut into the insulin molecule. If ketones are absent during low blood sugar states it is more likely that too much insulin is present (inhibiting ketone production). If ketones are present it is more likely that the counter hormones are not quite doing their job.

I hope this helps some. Best wishes.

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