Elevated C-peptide

An increase in C-peptide concentration above the normal range, indicating increased endogenous insulin secretion or reduced clearance of C-peptide.

• Fasting: 0.5-2.0 ng/mL or 0.17-0.66 nmol/L

• Postprandial: 2.0-6.0 ng/mL or 0.66-2.0 nmol/L

Causes

• Increased endogenous insulin production

  • Insulin resistance

  • Early type 2 diabetes mellitus with compensatory hyperinsulinemia

  • Obesity-associated hyperinsulinemia

  • Insulinoma

  • Cushing's syndrome

• Renal failure

• Medications: Sulfonylurea