Byetta and c-peptide..?

[barko]

So...

At my last Dr. appt. - he gives me a c-peptide test. (Measures insulin levels present)

BUT...I had eaten about 1.25 hours prior and had a shot of Byetta at that time. Byetta works by increasing insulin production and has a half-life of 2.4 hours. :confused:

Then he calls me to say my insulin production is fine...am I missing something here? Shouldn't the c-peptide be done without the influence of a drug that stimulates insulin secretion?

[barko]

Well here is an answer...

Found this:

"The C-peptide provides a snapshot recording of insulin production, which typically ranges between 0.5 and 3 nanograms (ng) per millileter (ml). In people with type 2 diabetes or no diabetes at all, eating anything up to eight hours before the exam can raise blood glucose levels, which makes the body produce more insulin-and can unnaturally alter the C-peptide test's results. Therefore, for the test to accurately reflect actual insulin production, it is important it be performed on a fasting patient."

"It [the C-peptide test] has to be done fasting," says Richard Bernstein, MD, FACE, FACN, CWS, director of the Diabetes Center in Mamaroneck, New York. "The amount of C-peptide depends on current insulin production."

A variety of medications can also affect the results.

One thing is this..

C-peptides are only created when endogenous insulin is produced, so when they run a c-peptide, it is able to distinguish between natural and injected insulin. But in my case (any anyone else who uses Byetta), the elevated insulin levels are "natural" because Byetta stimulates insulin secretion from the cells - it is not an injected insulin.

Guess I will give him a call and schedule a fasting c-peptide ;-)

[jenet]

Glad you found an answer. Not being Type 2 or using Byetta, I really didn't know how that would affect any results.

cheers,
j

[BlueSky]

. ......am I missing something here? Shouldn't the c-peptide be done without the influence of a drug that stimulates insulin secretion?
I agree with your reservation. If the purpose is to see how well the system is working, it needs to be a fasting, drug-free test. Perhaps the doctor was looking for an indication of how insulin resistant you are. As you are not injecting, the c-peptide test would reflect how much insulin is required to keep your blood glucose down. But ask your doctor - I am just guessing :D .