Early presymptomatic autoimmune T1D (Stages 1 and 2) can be identified through testing for autoantibodies (AAbs) in the blood1,2
Autoimmune T1D detection in the clinic
Collection of a blood sample for testing can be done by a simple finger prick.3 The four AAb tests recommended by the American Diabetes Association (ADA) Standards of Care are:4
GADA
(Glutamic acid decarboxylase 65 autoantibody)
- Common first detected AAb in children aged ≤15 years
- Adult-onset cases mostly present with GADA
- Associated with slower T1D progression
- Often found as a single AAb, especially in adults
IAA
(Insulin autoantibody)
- Common first detected AAb in young children
- More commonly detected in younger children
- Frequency declines with increasing age
- Not informative for those treated with insulin
IA-2A
(Insulinoma-associated antigen 2 autoantibody)
- Associated with more advanced islet autoimmunity
- Associated with faster T1D progression to stage 3
- IA-2A is also called islet cell autoantigen 512 (ICA512)
ZnT8A
(Zinc transporter 8 autoantibody)
- Presence can improve risk stratification in people with single GADA+, IAA+ or IA-2A+ status
Find out more about who to test here.
Glycaemic parameters to look for in autoimmune T1D4
| Blood test | Stage 1 Normoglycaemia | Stage 2 Dysglycaemia | Stage 3 Hyperglycaemia |
| Fasting plasma glucose (FPG) | <5.6 mmol/L | 5.6–6.9 mmol/L | ≥7.0 mmol/L |
| 120-min oral glucose tolerance test (OGTT) | <7.8 mmol/L | 7.8–11.0 mmol/L | ≥11.1 mmol/L |
| Glycated haemoglobin (HbA1c) | <39 mmol/mol (<5.7%) | 39–47 mmol/mol (5.7–6.4%) | ≥48 mmol/mol (≥6.5%) |
Adapted from Phillip M, et al. 2024.4
WHO recommends four diagnostic tests for Stage 3 autoimmune T1D:5
- FPG (≥7.0 mmol/L)
- 2-hour post-load plasma glucose after a 75 g OGTT (≥11.1 mmol/L)
- HbA1c (≥48 mmol/mol)
- Random blood glucose in the presence of signs and symptoms of diabetes (≥11.1 mmol/L)
If elevated values are detected in asymptomatic people, repeat testing, preferably with the same test, as soon as practicable on a subsequent day to confirm diagnosis.5
The number of AAbs detected, glycaemic status, and age may be used to guide frequency of monitoring.6
Find out more about monitoring guidance here.
Screening and monitoring for autoimmune T1D
Most screening initiatives for presymptomatic autoimmune T1D (Stages 1 and 2) are being performed in the context of research, but may become standard of care in parts of the world.3
In the UK, adults and children can be screened for autoimmune T1D through enrolment in research studies:7,8
- T1DRA Adults aged 18-70 years old
- ELSA Children aged 3-13 years old
ELSA and T1DRA are research studies independent of Sanofi.
Testing should be coupled with education and ongoing monitoring for those identified with islet AAbs.3
INDICATION: TZIELD is indicated to delay the onset of Stage 3 T1D in adult and paediatric patients 8 years of age and older with Stage 2 T1D.9
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Get in touchAAb, autoantibody; FPG, fasting plasma glucose; GADA, glutamic acid decarboxylase 65 autoantibody; HbA1c, glycated haemoglobin; IAA, insulin autoantibody; IA-2A, insulinoma-associated antigen 2 autoantibody; OGTT, oral glucose tolerance test; T1D, Type 1 diabetes; WHO, World Health Organization; ZnT8A, zinc transporter 8 autoantibody.
- Sims EK, et al. Diabetes. 2022; 71: 610–623.
- Ospelt E, et al. Clin Diabetes. 2024; 42(1): 17–26.
- Haller MJ, et al. Horm Res Paediatr. 2024; 97(6): 529–545.
- Phillip M, et al. Diabetes Care. 2024; 47(8): 1276–1298.
- World Health Organization. (2019). Classification of diabetes mellitus. Available at: https://www.who.int/publications/i/item/classification-of-diabetes-mellitus. Accessed November 2025.
- Simmons KMW, et al. Diabetes Technol Ther. 2023; 25(11): 790–799.
- The Type 1 Diabetes Risk in Adults (T1DRA) Study. Available at: https://t1dra.bristol.ac.uk/. Accessed November 2025.
- The ELSA Study. Available at: https://www.elsadiabetes.nhs.uk/. Accessed November 2025.
- TZIELD® (teplizumab) UK Summary of Product Characteristics. 2025.
MAT-XU-2500762 (v1.0) | November 2025