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Insulin Autoantibodies (IAA)

Measures antibodies to insulin, used to look for autoimmune (type 1) diabetes before insulin treatment or to find antibodies to injected insulin.

AI-verified against cited sources. Awaiting expert reviewAlso called IAALOINC 8072-1

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What it is

Insulin autoantibodies (IAA) are antibodies the immune system makes against insulin. This test measures how much of that antibody is in your blood. It is mainly used when type 1 diabetes is suspected, or being looked for, in someone who has not started insulin treatment. In people who take insulin, the same test can pick up antibodies made in response to the injected insulin.

Why it matters

IAA is one of four islet antibodies (GAD65, IA-2, insulin and ZnT8) used to find autoimmune, or type 1, diabetes. In young children it is often the first one to appear. Having two or more islet antibodies, even with normal blood sugar, is called stage 1 type 1 diabetes. Injected insulin can cause the same antibodies, so the result only helps with autoimmune diabetes if the blood was drawn before insulin treatment started or within about 2 weeks of diagnosis. In rare cases, antibodies to insulin cause low blood sugar in people who have never taken insulin.

If it’s high

A positive result means antibodies to insulin were found. If you take insulin, this usually reflects a response to the injected insulin. If you have never taken insulin, it can be a sign of autoimmune (type 1) diabetes or a risk of it, especially in young children. A single positive result on its own is not a diagnosis, and a first positive is usually confirmed with a second test.

Common causes

  • Antibodies made in response to injected insulin, if you take insulin
  • A single low-level positive that later goes away (up to half of children with one antibody become negative later)
  • Autoimmune (type 1) diabetes or early-stage type 1 diabetes, especially in young children
  • Rarely, insulin autoimmune syndrome: antibodies in people who have never taken insulin that cause low blood sugar episodes

What can help

  • Tell your clinician whether you take insulin and when you started, because it changes how the result is read
  • Ask whether a second test, or the other islet antibodies (GAD65, IA-2 and ZnT8), should be checked
  • If you have episodes of shakiness, sweating, confusion or fainting, ask your clinician how to look into the cause

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–0.4 U/mL. Source: ARUP Laboratories, Journal of Clinical Endocrinology & Metabolism 2018;103:3845-3855.

What can affect your result

  • Insulin treatment: injected insulin can cause antibodies, which changes the meaning of the result
  • Age: in young children, insulin antibodies are often the first islet antibody to appear
  • Method and units: radioimmunoassays and ELISAs use different cutoffs
  • Family history of type 1 diabetes
  • Insulin treatment: people who take insulin make antibodies to the injected insulin, and this test can detect them. The result then cannot show whether the antibodies come from autoimmune diabetes. ARUP does not recommend the test for people who have taken insulin for more than 2 weeks, and research studies take samples within about 2 weeks of diagnosis to limit the effect of antibodies caused by insulin treatment.
  • Radioimmunoassay versions can be affected by recent radioactive isotope scans or treatments. Mayo asks that none be given in the 24 hours before the blood draw.
  • Methods differ. Radioimmunoassays and ELISAs use different units and cutoffs, and the insulin antibody test varies more between labs than the other islet antibody tests.
  • ARUP rejects plasma and hemolyzed or lipemic samples.

When to talk to a clinician

Seek emergency care if you have very high blood sugar together with vomiting, belly pain, fast or deep breathing, fruity-smelling breath or confusion. These can be signs of diabetic ketoacidosis. Low blood sugar with confusion, a seizure or fainting is also an emergency, so call 911 or your local emergency number. Contact a clinician soon for new constant thirst, frequent urination or weight loss.

Questions you could ask

  • Why was this test ordered, and what will we do with the result?
  • Does my lab's cutoff differ from other labs, and how should I compare future results?
  • Could this result come from the insulin I take, or from autoimmune diabetes?
  • Should we repeat the test or check the other islet antibodies?
  • Do my blood sugar patterns, including any lows, fit with this result?

Questions people ask

I take insulin. Why is my insulin antibody positive?

Insulin you inject can lead your body to make antibodies against it, and this test can pick them up. ARUP notes that its assay picks up antibodies to injected insulin. A positive result in someone who takes insulin usually reflects that response, so ask your clinician what it means for you.

Why is this test only helpful before starting insulin?

Once insulin treatment starts, the immune system can make antibodies to the injected insulin, which looks the same on the test. For autoimmune diabetes, studies collect the sample within about 2 weeks of diagnosis so that treatment has little effect on the result.

Show the science and sources

For clinicians and researchers

Insulin autoantibodies are measured by fluid-phase radiobinding assays (the reference method), ELISA or newer electrochemiluminescence and bridging assays. Radiobinding assays detect both high- and low-affinity antibodies, and low-affinity IAA, especially as a single antibody, are poor predictors of type 1 diabetes. IAA is the most technically challenging islet antibody to measure and varies the most between labs, so results are best read against the cutoff of the lab that ran them. The ADA also advises confirming a first positive with a second test. Result scales differ by assay: ARUP's Kronus radioimmunoassay uses arbitrary units equal to U/mL with a positive cutoff above 0.4; the Esoterix assay in Mayo's catalog measures insulin-I125 binding capacity with a cutoff of 5.0 uU/mL; a published ELISA used 10.0 U/mL. ARUP notes that its assay detects antibodies to both endogenous and exogenous insulin and that the size of the result is not related to disease progression. In research cohorts, insulin autoantibodies tend to appear before GAD65 antibodies in young children, and higher levels of insulin and IA-2 autoantibodies are linked to earlier symptoms. For presymptomatic type 1 diabetes, studies draw samples within 2 weeks of diagnosis to avoid antibodies induced by insulin treatment. Insulin autoimmune syndrome causes hyperinsulinemic hypoglycemia in insulin-naive people. Antibody binding skews insulin and C-peptide ratios, which can mimic other causes of hypoglycemia.

LOINC 8072-1 (primary), 56546-5, 5232-4, 2481-0. Specimen: serum.

Sources

  1. Insulin Antibody (ARUP test 0099228), ARUP Laboratories (2026)
  2. Insulin Autoantibodies (IAA) (Mayo Clinic Laboratories test FINAB), Mayo Clinic Laboratories (Extended Catalog mirror, testcatalog.org) (2026)
  3. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2025, American Diabetes Association, Diabetes Care 2025;48(Suppl 1):S27-S49 (2025)
  4. Staging presymptomatic type 1 diabetes: a scientific statement of JDRF, the Endocrine Society, and the American Diabetes Association, Diabetes Care 2015;38:1964-1974 (2015)
  5. ISPAD Clinical Practice Consensus Guidelines 2024: Screening, Staging, and Strategies to Preserve Beta-Cell Function in Children and Adolescents with Type 1 Diabetes, Hormone Research in Paediatrics 2024;97:529-545 (2024)
  6. Natural history of a pediatric cohort with islet autoantibody positivity: a single-center retrospective cohort study, Journal of the Endocrine Society 2026;10:bvag087 (2026)
  7. Identifying Insulin Autoantibodies With Differential Risk in Type 1 Diabetes With a Novel Bridging ELISA, Diabetes 2026;75:519-525 (2026)
  8. Assessment and Management of Anti-Insulin Autoantibodies in Varying Presentations of Insulin Autoimmune Syndrome, Journal of Clinical Endocrinology & Metabolism 2018;103:3845-3855 (2018)
  9. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 8072-1), U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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