What is the clinical significance of C-peptide levels?

C-peptide levels hold clinical significance primarily in distinguishing between type 1 and type 2 diabetes. C-peptide is a byproduct of insulin production, formed when proinsulin is cleaved into insulin and C-peptide. In type 1 diabetes, which is characterized by autoimmune destruction of pancreatic beta cells, low or undetectable C-peptide levels are typically found because insulin production is severely impaired or absent.

In contrast, type 2 diabetes is often associated with insulin resistance, where the body produces insulin but does not effectively utilize it. As a result, C-peptide levels can be normal or elevated in individuals with type 2 diabetes, reflecting the relative ability of the pancreas to produce insulin. Therefore, measuring C-peptide levels helps clinicians determine whether the patient's diabetes is characterized by an absence of insulin production (type 1) or a more complex interaction of insulin resistance and possible insulin deficiency (type 2).

By assessing C-peptide levels, healthcare providers can tailor their treatment approaches based on the patient's specific type of diabetes, making this measurement a valuable tool in diabetes management.