C Peptide
Released in equal amounts to insulin, so it reflects how much insulin the pancreas is producing.
Typical reference range
| Range | Unit |
|---|---|
| 0.3–1.3 | nmol/l |
What C Peptide measures
C-peptide is released by the pancreas in equal amounts to insulin whenever insulin is made, so measuring it gives a useful picture of how much insulin your own body is producing. Because it comes directly from the pancreas, it reflects native insulin output even in people who also take injected insulin.
Clinicians sometimes use C-peptide to help tell apart types of diabetes and to assess how well the pancreas is still making insulin. It is often read together with glucose, since the two together show whether the body is producing enough insulin for the amount of sugar in the blood. On its own the number says little; its meaning depends on the surrounding clinical picture.
What a high C Peptide can mean
A high C-peptide means the pancreas is producing a lot of insulin. The most common reason is insulin resistance, where the body's cells respond poorly to insulin and the pancreas compensates by making more of it. This pattern is often seen in type 2 diabetes and metabolic syndrome, where extra insulin is needed to keep glucose under control.
Less commonly, other causes can raise C-peptide. Because of this, the result is always interpreted alongside glucose and the broader clinical situation rather than in isolation. A high value paired with normal or high glucose typically points toward the body working hard to manage blood sugar. A clinician weighs your history, symptoms, and other tests before drawing any conclusion.
What a low C Peptide can mean
A low C-peptide means little insulin is being produced by the pancreas. This is the expected pattern in type 1 diabetes, where the insulin-producing cells are damaged, and in advanced pancreatic insufficiency, where the pancreas can no longer make enough insulin.
The result is most informative when read together with glucose. In someone whose glucose is high, a low C-peptide points toward insulin deficiency rather than insulin resistance, since the body is not producing the insulin it needs. This distinction can matter for how diabetes is understood and managed. A clinician interprets the value in the context of your glucose, symptoms, and overall clinical picture rather than treating the number alone.
Track your C Peptide over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.