Quantitative Enzyme-Linked Immunosorbent Assay
Useful to establish autoimmune etiology in previously diagnosed T1DM.
Diabetes mellitus (DM) refers to a group of metabolic disorders characterized by hyperglycemia that results from defects in insulin secretion, insulin action, or both. Type 1 DM (T1DM) is less common than type 2 DM (T2DM) and is characterized by insulin deficiency, which often results from the autoimmune-mediated destruction of insulin-producing cells. The detection of diabetes-associated autoantibodies confirms an autoimmune etiology for that individual.
Indications for Insulin Antibody Testing
Patient should have been previously diagnosed with DM
Most useful in children or in adults without traditional risk factors for T2DM
GAD, glutamic acid decarboxylase antibody; IA-2, islet antigen-2; IAA, insulin antibody; ICA, islet cell cytoplasmic antibody; LADA, latent autoimmune diabetes of the adult; MODY, maturity-onset diabetes of the young; ZnT8, zinc transporter 8 antibody
Diabetes Mellitus Type 1 Overview
1.25 million in the United States
Age of Onset
Most common in children but can develop in individuals of any age, especially in late 30s or early 40s
- Excessive thirst, hunger, and urination
- Fatigue, nausea, blurred vision
- Unexplained weight loss (obesity is rare at initial diagnosis)
- Possibly, other autoimmune disorders
- Caused by autoimmune-mediated destruction of insulin-producing beta cells of the islets of Langerhans in the pancreas
- Five major autoantibodies of diagnostic interest:
- Antibodies may be present in individuals years before the onset of clinical symptoms.
- Presence in individuals with diabetes confirms an autoimmune etiology.
Moderate sensitivity, high specificity in newly diagnosed T1DM
- Presence of antibodies may decrease with long-term disease.
- Insulin antibody testing loses specificity once patient has been on exogenous insulin for >2 weeks.
- Presence of multiple insulin antibodies (GAD, IA-2, IAA, ICA, and ZnT8) is predictive of T1DM.
- If one autoantibody is found, others should be assayed; the risk of T1DM increases (>90%) if an individual tests positive for two or more autoantibodies.
- For further risk stratification, HLA-DR or HLA-DQ genotyping may be helpful.
- Negative test results do not rule out autoimmune diabetes; autoantibody response varies by individuals.
- Presence of a single autoantibody in the absence of clinical symptoms has low predictive value (1-2% in healthy individuals).
- Not all individuals with antibodies will develop T1DM.
- Do not use to monitor or diagnose T1DM.
- IAA test does not differentiate between antibodies specific for endogenous and exogenous forms of insulin.
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American Diabetes Association. Standards of Medical Care in Diabetes–2021. [Published: Jan 2021; Accessed: Jun 2021]
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National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Monogenic diabetes (neonatal diabetes mellitus & MODY). [Last reviewed: Nov 2017; Accessed: Jun 2021]
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