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From Buffalo, New York, USA:

I'm having a C-Peptide test done soon. How will external insulin affect the results? What other things can affect the results?


The best time to have a C-Peptide test is to have it with a meal challenge. Therefore, two hours after a meal, when your sugar is peaking, is a good time to have the test performed. If you have it fasting and the sugar is low, the C-Peptide may be appropriately low. When you take exogenous insulin, the insulin will not register in the C-Peptide assay. However, if you are aggressive with your insulin dose at a meal, and the glucose comes down to a low normal value, it will not be a strong stimulus for insulin to be secreted and for the C-Peptide level to be picked up on the laboratory test.


Original posting 29 Apr 2008
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Last Updated: Tuesday April 06, 2010 15:10:16
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