What are expected insulin and C-peptide levels in patients injecting exogenous insulin?

In patients injecting exogenous insulin, the expected levels of insulin will be high because they are directly administering insulin into their bodies. However, the levels of C-peptide will be low.

C-peptide is a byproduct of insulin production in the pancreas. When the pancreas releases insulin into the bloodstream, C-peptide is released in equal amounts. Therefore, in the context of exogenous insulin use, since patients are receiving insulin from an external source, the pancreas does not produce additional insulin, and as a result, it will not release C-peptide. Consequently, with high levels of injected insulin and low levels of endogenous C-peptide due to the lack of natural insulin production, the findings align accurately with the expected scenario.

This understanding is crucial, particularly in differentiating between types of diabetes or in evaluating for conditions where endogenous insulin production is a factor.