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Insulin Autoantibody
Test CodeINSAB
Preferred Specimen
1 mL serum
Minimum Volume
0.2 mL
Transport Container
Transport tube
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 28 days
Refrigerated: 28 days
Frozen: 90 days
Refrigerated: 28 days
Frozen: 90 days
Methodology
Radiobinding Assay (RBA)
Setup Schedule
Sun, Tues, Thurs
Report Available
3-5 days
Limitations
In diabetic children <14 years of age (identified by urine screening), the frequency of insulin antibodies (IAA) and islet cell antibodies (ICA) are 43-56% and 84%, respectively; the frequency of both is 40%, and the frequency of one or both is 88%.4 In the same study, cohorts using ICA, GAD-65 antibodies and IAA, sensitivities and specificities are 93% and 93% for any positive, respectively, and 39% and >99%, respectively, for all positives. IAA are found at onset of diabetes in only 4% of adults, but are universally present in diabetic children <4 years old at onset. The predictive value of both tests (ICA and IAA) is 60-77% in first-degree relatives of patients with IDDM for the development of IDDM in 5-10 years.
Reference Range
<0.4 U/mL
Clinical Significance
Key clinical use and differentiators
Measurement of Insulin Autoantibody (IAA) is used to: 1. Screen for presymptomatic type 1 diabetes (T1D) in individuals with a family history of T1D or those known to have a high-risk HLA genotype, 2. Distinguish between T1D, type 2 diabetes mellitus (T2D), and atypical forms of diabetes such as latent autoimmune diabetes in adults (LADA). [1] Insulin Autoantibody (IAA) is used to help predict the need for insulin treatment in adults with diabetes who have not received treatment with insulin. [1]
Intended Clinical Use
This test is crucial for differentiating between T1D and T2D. It is important to note that classifying diabetes type can be challenging at the time of presentation, and misdiagnosis can occur in approximately 40% of adults with new T1D. [1]
Identifying individuals affected by stage 1 T1D is important for applying eligibility criteria to drugs, such as Teplizumab, which have demonstrated the ability to delay the transition of stage 1 to stage 3 T1D in clinical trials [2,3]
IAA has some distinctive features, including that usually it is the first detected autoantibody in young children, [4] its appearance is more common in younger children [5] and its frequency of appearance declines with age. IAA is not informative for individuals treated with insulin, who often develop antibodies in response to injected insulin. [6]
Limitations
T1D is classified into three stages, with stages 1 and 2 considered presymptomatic. Since the presence of stage 1 and 2 T1D requires at least two islet autoantibodies, relying solely on IAA as a screening test limits the ability to make an accurate diagnosis. Professional organizations, including the American Diabetes Association (ADA), recommend using tests for all four islet cell autoantibodies: IAA, glutamic acid decarboxylase (GAD65), Zinc Transporter 8 (ZnT8), and islet cell antigen 2 antibody (IA-2).[1]
References
1. American Diabetes Association Professional Practice C. 2. Diagnosis and Classification of Diabetes: Standards of care in Diabetes-2025. Diabetes Care. 2025;48:S27-S49. doi: 10.2337/dc25-S002
2. Herold KC, Gitelman SE, Gottlieb PA, Knecht LA, Raymond R, Ramos EL. Teplizumab: A Disease-Modifying Therapy for Type 1 Diabetes That Preserves beta-Cell Function. Diabetes Care. 2023;46:1848-1856. doi: 10.2337/dc23-0675
3. Ramos EL, Dayan CM, Chatenoud L, Sumnik Z, Simmons KM, Szypowska A, Gitelman SE, Knecht LA, Niemoeller E, Tian W, et al. Teplizumab and beta-Cell Function in Newly Diagnosed Type 1 Diabetes. N Engl J Med. 2023;389:2151-2161. doi: 10.1056/NEJMoa2308743
4. Hummel S, Ziegler AG. Early determinants of type 1 diabetes: experience from the BABYDIAB and BABYDIET studies. Am J Clin Nutr. 2011;94:1821S-1823S. doi: 10.3945/ajcn.110. 000646
5. Ziegler AG, Bonifacio E, Group B-BS. Age-related islet autoantibody incidence in offspring of patients with type 1 diabetes. Diabetologia. 2012;55:1937-1943. doi: 10.1007/ s00125-012-2472-x
6. Phillip M, Achenbach P, Addala A, Albanese-O'Neill A, Battelino T, Bell KJ, Besser REJ, Bonifacio E, Colhoun HM, Couper JJ, et al. Consensus Guidance for Monitoring Individuals With Islet Autoantibody-Positive Pre-Stage 3 Type 1 Diabetes. Diabetes Care. 2024. doi: 10.2337/ dci24-0042
Measurement of Insulin Autoantibody (IAA) is used to: 1. Screen for presymptomatic type 1 diabetes (T1D) in individuals with a family history of T1D or those known to have a high-risk HLA genotype, 2. Distinguish between T1D, type 2 diabetes mellitus (T2D), and atypical forms of diabetes such as latent autoimmune diabetes in adults (LADA). [1] Insulin Autoantibody (IAA) is used to help predict the need for insulin treatment in adults with diabetes who have not received treatment with insulin. [1]
Intended Clinical Use
This test is crucial for differentiating between T1D and T2D. It is important to note that classifying diabetes type can be challenging at the time of presentation, and misdiagnosis can occur in approximately 40% of adults with new T1D. [1]
Identifying individuals affected by stage 1 T1D is important for applying eligibility criteria to drugs, such as Teplizumab, which have demonstrated the ability to delay the transition of stage 1 to stage 3 T1D in clinical trials [2,3]
IAA has some distinctive features, including that usually it is the first detected autoantibody in young children, [4] its appearance is more common in younger children [5] and its frequency of appearance declines with age. IAA is not informative for individuals treated with insulin, who often develop antibodies in response to injected insulin. [6]
Limitations
T1D is classified into three stages, with stages 1 and 2 considered presymptomatic. Since the presence of stage 1 and 2 T1D requires at least two islet autoantibodies, relying solely on IAA as a screening test limits the ability to make an accurate diagnosis. Professional organizations, including the American Diabetes Association (ADA), recommend using tests for all four islet cell autoantibodies: IAA, glutamic acid decarboxylase (GAD65), Zinc Transporter 8 (ZnT8), and islet cell antigen 2 antibody (IA-2).[1]
References
1. American Diabetes Association Professional Practice C. 2. Diagnosis and Classification of Diabetes: Standards of care in Diabetes-2025. Diabetes Care. 2025;48:S27-S49. doi: 10.2337/dc25-S002
2. Herold KC, Gitelman SE, Gottlieb PA, Knecht LA, Raymond R, Ramos EL. Teplizumab: A Disease-Modifying Therapy for Type 1 Diabetes That Preserves beta-Cell Function. Diabetes Care. 2023;46:1848-1856. doi: 10.2337/dc23-0675
3. Ramos EL, Dayan CM, Chatenoud L, Sumnik Z, Simmons KM, Szypowska A, Gitelman SE, Knecht LA, Niemoeller E, Tian W, et al. Teplizumab and beta-Cell Function in Newly Diagnosed Type 1 Diabetes. N Engl J Med. 2023;389:2151-2161. doi: 10.1056/NEJMoa2308743
4. Hummel S, Ziegler AG. Early determinants of type 1 diabetes: experience from the BABYDIAB and BABYDIET studies. Am J Clin Nutr. 2011;94:1821S-1823S. doi: 10.3945/ajcn.110. 000646
5. Ziegler AG, Bonifacio E, Group B-BS. Age-related islet autoantibody incidence in offspring of patients with type 1 diabetes. Diabetologia. 2012;55:1937-1943. doi: 10.1007/ s00125-012-2472-x
6. Phillip M, Achenbach P, Addala A, Albanese-O'Neill A, Battelino T, Bell KJ, Besser REJ, Bonifacio E, Colhoun HM, Couper JJ, et al. Consensus Guidance for Monitoring Individuals With Islet Autoantibody-Positive Pre-Stage 3 Type 1 Diabetes. Diabetes Care. 2024. doi: 10.2337/ dci24-0042
