How are C-peptide levels used to diagnose hypoglycemia (low blood sugar)?

Updated: Jul 23, 2020
  • Author: Osama Hamdy, MD, PhD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Obtain C-peptide levels any time an elevated insulin level is obtained. Endogenous hyperinsulinemia from insulinoma is associated with elevated C-peptide concentrations with concurrent hypoglycemia. Exogenous hyperinsulinemia from injected insulin results in low concentrations of C-peptide, both because of the effect of the associated hypoglycemia and because of the direct suppressive effect of insulin on the pancreatic beta cell. [16]

C-peptide levels are elevated in insulinoma, normal or low with exogenous insulin, and elevated with oral sulfonylureas.

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