$16.00
Priced per marker, with baseline labs included. You’ll see your total before you pay.
Metabolism & organs
C-peptide test
Byproduct of insulin production; distinguishes endogenous insulin (made by pancreas) from injected insulin and assesses beta-cell function.
At a glance
In about 5 days
Most results are ready in about 5 days. Some specialty markers can take up to 21 days.
Check before your draw
This marker has no preparation tag, but it can still need preparation. Contact us before your draw if you’re not sure.
Walk in at Quest
Your lab order arrives by email. Most Quest locations take walk-ins, so bring it with a photo ID.
What it measures
When your pancreas, the organ behind your stomach, makes insulin, it releases C-peptide at the same time. Measuring it can show how much insulin your own body is making.
Why it matters for women
If you had diabetes during pregnancy, or diabetes shows up afterward, this test can help show how much insulin your body still makes, which helps tell the kinds of diabetes apart. With PCOS, insulin resistance can push the pancreas to make extra insulin, which may show as a higher level.
You might check it if…
- a doctor isn’t sure which kind of diabetes is involved
- you had diabetes during a past pregnancy
- you live with PCOS or insulin resistance
- you’ve had low blood sugar spells without a clear reason
What your result may mean
High C-peptide: what it may mean
High C-peptide may mean your pancreas is making a lot of insulin. With high blood sugar, it may point to insulin resistance or type 2 diabetes, and with PCOS, insulin resistance can push the pancreas to make extra. With low blood sugar, it may point to an insulin-making tumor (insulinoma) or to certain diabetes pills. Reduced kidney function can also raise it, because the kidneys help clear it, and a recent meal can push it up. A glucose result from the same sample can make this number much easier to read.
Low C-peptide: what it may mean
Low C-peptide may mean your pancreas is making little insulin, as can happen with type 1 diabetes or when insulin-making cells wear out in long-standing diabetes (beta-cell exhaustion). If diabetes turns up during or after pregnancy, this result may help tell the kinds of diabetes apart. Long fasting can lower it, and low blood sugar with low C-peptide may point to insulin coming from outside the body. You may notice thirst, frequent urination or weight loss if insulin is running short. Glucose and diabetes antibody tests can help a clinician sort out the type of diabetes.
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No insurance required · HSA/FSA eligible · No subscription
These notes provide context and do not diagnose a condition. Not yet available in NY, NJ, RI, HI, ND, SD or WV.