From the Guidelines
In type 1 diabetes, the presence of two or more autoantibodies is a significant risk factor for clinical disease, and having multiple confirmed islet autoantibodies increases the risk of developing type 1 diabetes substantially. The most commonly tested antibodies include glutamic acid decarboxylase (GAD) antibodies, islet cell antibodies (ICA), insulin autoantibodies (IAA), and zinc transporter 8 (ZnT8) antibodies. According to the most recent guidelines 1, stage 1 of type 1 diabetes is defined by the presence of two or more of these autoantibodies and normoglycemia. While a single positive antibody can indicate autoimmunity, patients with two or more positive antibodies have a much higher risk of progression to clinical disease. Some key points to consider in the diagnosis of type 1 diabetes include:
- The presence of autoantibodies reflects the autoimmune process where the body's immune system attacks insulin-producing beta cells in the pancreas 1
- Antibody testing is just one component of diagnosis, which also relies on clinical presentation, blood glucose levels, and sometimes C-peptide measurements to assess insulin production 1
- Some patients with type 1 diabetes may even be antibody-negative at diagnosis, particularly adults with slower-onset disease 1
- The risk of developing type 1 diabetes increases substantially with each additional positive antibody, and the 5-year risk of developing symptomatic type 1 diabetes is 44% overall for those with two or more autoantibodies 1.
From the Research
Type 1 Diabetes Antibodies
- The presence of islet autoantibodies is a reliable biomarker to identify individuals at high risk of developing type 1 diabetes 2.
- Autoantibodies against Glutamic Acid Decarboxylase (GADA), insulinoma antigen-2 (IA-2A), insulin (IAA), and Zinc Transporter 8 (ZnT8A) are commonly used to distinguish Latent Autoimmune Diabetes in Adults (LADA) from phenotypically type 2 diabetes 3.
- Being multiple autoantibody positive has a high predictive value of childhood type 1 diabetes, and is more common in childhood diabetes compared to adult onset diabetes 3.
Number of Antibodies Required for Diagnosis
- There is no specific number of antibodies that need to be positive for a diagnosis of type 1 diabetes, as the presence of one or more autoantibodies can indicate an increased risk of developing the disease 4, 2, 3, 5, 6.
- However, the presence of multiple autoantibodies, such as GADA, IA-2A, and ZnT8A, can help to stratify the clinical phenotype and predict the risk of future type 1 diabetes 6.
- The use of GADAs, IA-2As, and ZnT8As in combination can allow for a more accurate diagnosis and characterization of adult-onset autoimmune diabetes 6.