What is the role of C peptide in managing uncontrolled type 2 diabetes?
—Ndukwe H. Odeluga, MD, Bakersfield, Calif.
Cleaved from proinsulin to make mature insulin, C peptide can be considered a marker of endogenous insulin secretion. It is used in research studies on diabetes patients to help classify the etiology of their disease, as low levels would indicate the insulin-deficient state of type 1 diabetes, while high levels would be indicative of insulin resistance, as in type 2 diabetes. C peptide has no role in managing uncontrolled type 2 diabetes. It is useful, however, in differentiating insulinoma (which would result in high C-peptide levels and high insulin levels) from hypoglycemia due to surreptitious insulin intake (which would result in low C-peptide levels despite high insulin levels).
—Susan Kashaf, MD, MPH (104-1)