Clinical Information

C-peptide should be interpreted together with concurrent glucose results, particularly in the diagnostic evaluation of hypoglycemia, including the assessment of factitious hypoglycemia from surreptitious insulin use, evaluation for insulinoma, and determination of physiologic suppressibility of endogenous insulin secretion during insulin-induced hypoglycemia (C-peptide suppression test). C-peptide is also useful for assessing endogenous insulin secretory reserve in diabetic patients with insulin autoantibodies or those receiving insulin therapy, including monitoring pancreatic or islet transplant function and immunomodulatory treatments aimed at slowing early type 1 diabetes progression. Fasting C-peptide may be elevated in individuals with BMI >25. As with all immunoassays, heterophile or human anti-animal antibodies may interfere and produce falsely elevated or falsely decreased results; results should always be interpreted in the full clinical context.