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Insulin Concentration (Serum/Plasma)

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

This test measures the amount of insulin, a hormone produced by the pancreas, in your blood. It helps assess how well your body regulates blood sugar.

Quick summary

["Helps diagnose or monitor conditions affecting insulin production or blood sugar control."]

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

Key facts at a glance

LOINC
56946-7
Short code
Insulin 2D p chal SerPl-aCnc
Synonyms
Insulin 2D p chal SerPl-aCnc
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

Why This Test Is Done

Your doctor may order this test if you have symptoms of diabetes, such as frequent urination, excessive thirst, unexplained weight loss, or fatigue. It may also be used to evaluate insulin resistance, pancreatic issues, or to monitor treatment for conditions like diabetes or hypoglycemia.

Sample Collection and Preparation

A blood sample is taken from a vein, usually in your arm. The sample is collected in a special tube that prevents clotting. The blood is then separated into serum (liquid part after clotting) or plasma (liquid part without clotting) for testing. This test can be done at a clinic, hospital, or lab.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a glucose-insulin study. If you’re pregnant, have a chronic condition, or are on certain medications, let your doctor know beforehand.

What the Results Mean

Results are compared to standard ranges for your age, sex, and health status. Low insulin levels may indicate diabetes, pancreatic disorders, or other metabolic issues. High levels could suggest insulin resistance, tumors, or other endocrine problems. Your doctor will interpret results in the context of your overall health.

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

Serum/Plasma Insulin

Frequently asked questions

What causes low insulin levels?
Low insulin levels can result from conditions like diabetes (especially type 1), pancreatic diseases (e.g., pancreatitis, cystic fibrosis), or certain medications. Rarely, genetic disorders or autoimmune conditions may also contribute. If you experience symptoms like fatigue, weight changes, or frequent infections, discuss these with your doctor.
How is insulin tested differently from glucose?
Insulin is measured in serum or plasma, while glucose tests often use whole blood or capillary blood. Insulin tests are typically done after fasting or in response to glucose challenges (e.g., oral glucose tolerance tests). Unlike glucose, which is directly measured, insulin levels are often interpreted alongside glucose readings to assess insulin sensitivity or deficiency.
Can insulin levels change with diet or exercise?
Yes. Eating a high-carbohydrate meal can temporarily spike insulin levels, while exercise may lower them by improving insulin sensitivity. Fasting insulin levels are often measured to assess baseline function, but dynamic changes (e.g., post-meal) may be evaluated in specific studies.
  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