C Peptide test results are measured in nanograms/millilitres (ng/mL) or nanomoles/millimetres (nmol/mL). The normal range for a C Peptide test is between 0.51 to 2.72 ng/mL or 0.17 to 0.9 nmol/mL.
Abnormal C Peptide test results indicate the presence of a disorder with insulin levels.
If your C Peptide level is higher than normal, it can mean that your body produces too much insulin, indicating a metabolic disorder with insulin.
However, some other causes of a high C Peptide level include:
- Tumours, known as insulinomas
- Insulin resistance
- Renal diseases
- Cushing syndrome, an endocrine disorder
Low C peptides are usually indicative of the hampered production of insulin. This may be due to:
- Type 1 diabetes (people with type 1 diabetes have lower C peptide levels than people with type 2 diabetes)
- LADA, latent autoimmune diabetes in adults
- Impaired functioning of the pancreas
- Prolonged fasting
A class of diabetes drugs, known as sulfonylureas, can also raise your C Peptide levels. Therefore, always inform your healthcare provider about any current drug regimens to ensure they come to accurate conclusions.