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Proinsulin, Serum/Plasma — Substance Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures the amount of proinsulin, a precursor of insulin, in blood. Proinsulin testing can help evaluate pancreatic beta-cell function and insulin production.

Quick summary

["Elevated proinsulin may reflect reduced insulin production or impaired processing of proinsulin into insulin."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
27882-0
Short code
Proinsulin SerPl-sCnc
Synonyms
Proinsulin SerPl-sCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
2.6
Ref high
24.9
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83525
SNOMED
413618004
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

Proinsulin is an inactive precursor made by the pancreas that is converted into active insulin. This blood test measures the concentration of proinsulin in serum or plasma and can provide information about how the pancreas is producing and processing insulin.

Why might I need this test?

Your clinician may order this test when evaluating diabetes that is difficult to characterize, suspected insulin resistance, or symptoms suggesting excess insulin production. It may also be used in the assessment of pancreatic disorders or insulin-producing tumors.

How is the test performed?

A blood sample is collected, usually from a vein, and the serum or plasma is analyzed in a laboratory using an immunoassay or another validated measurement method. The result is reported as a concentration.

How do I prepare for the test?

Follow your clinician's instructions about fasting, medicines, and the timing of the blood draw. Because glucose and insulin levels can affect the interpretation of proinsulin, the test is often measured under standardized conditions or alongside other diabetes tests.

Reference range

Fasting: 2.6-24.9 μIU/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Proinsulin

Frequently asked questions

Is proinsulin the same as insulin?
No. Proinsulin is the inactive precursor that the pancreas converts into active insulin. A small amount normally remains in the blood.
What does a high proinsulin result mean?
It may indicate that the pancreas is producing more proinsulin than is being efficiently converted into insulin, or that insulin production and secretion are stressed. The result must be interpreted with symptoms, glucose and insulin tests, and other clinical findings.
Does the test require fasting?
Fasting may be recommended in some situations, especially when the result will be interpreted alongside glucose and insulin levels. Ask your clinician whether you should fast and how long beforehand.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy