Type 1 diabetes autoantibody screening: who is offered it, what is measured, and what the stages mean
A blood test for islet autoantibodies can show a higher risk of type 1 diabetes before symptoms start. The ADA says this screening should be offered to people with a family history of type 1 diabetes or otherwise known elevated genetic risk. (ADA, 2026) This page explains the test, the three stages and how a positive result is followed up.
What the test looks for
Type 1 diabetes develops when the body's immune system destroys the cells in the pancreas that make insulin, called beta cells. (NIDDK, 2025) Autoantibodies are proteins made by the immune system that attack healthy tissues and cells by mistake. (NIDDK, 2025) The ADA recommends screening for presymptomatic type 1 diabetes by testing autoantibodies against: (ADA, 2026)
- insulin;
- glutamic acid decarboxylase (GAD);
- islet antigen 2 (IA-2);
- zinc transporter 8 (ZnT8).
Who is offered screening
- ADA: autoantibody-based screening for presymptomatic type 1 diabetes should be offered to those with a family history of type 1 diabetes or otherwise known elevated genetic risk (recommendation 2.7, grade B). (ADA, 2026)
- NIDDK: if you have a parent or sibling with type 1 diabetes, your health care professional may suggest a test for autoantibodies, even if you don't have any symptoms. (NIDDK, 2025)
- Research programs: TrialNet is a research network that offers autoantibody testing to some family members of people with type 1 diabetes. (NIDDK, 2025)
- Most people have no relative with it: family history raises the risk, but about 90% of people who develop type 1 diabetes do not have a known relative with the disease. (ADA, 2026)
The ADA notes that 25% to 50% of people with type 1 diabetes are diagnosed with diabetic ketoacidosis (DKA), which is life threatening, and that finding high blood sugar early can help prevent DKA at diagnosis. (ADA, 2026)
The three stages of type 1 diabetes
The ADA stages type 1 diabetes as follows. (ADA, 2026)
| Stage | Autoantibodies | Blood sugar | Symptoms |
|---|---|---|---|
| Stage 1 | Multiple islet autoantibodies | Normal: no impaired fasting glucose or impaired glucose tolerance, normal A1C | None (presymptomatic) |
| Stage 2 | Islet autoantibodies (usually multiple) | Dysglycemia, defined by one or more of: fasting plasma glucose 100 to 125 mg/dL (5.6 to 6.9 mmol/L); 2-hour plasma glucose 140 to 199 mg/dL (7.8 to 11.0 mmol/L); A1C 5.7% to 6.4% (39 to 47 mmol/mol) or an A1C increase of 10% or more | None (presymptomatic) |
| Stage 3 | Autoantibodies may become absent | Diabetes by standard criteria | Symptomatic |
- Stage 1 risk: about 44% develop symptomatic type 1 diabetes within 5 years, but this varies considerably with the number, titer and type of autoantibodies, the age they first appeared and genetic risk. (ADA, 2026)
- Stage 2 risk: at the time of progression to stage 2, the risk of stage 3 is about 60% within 2 years and about 75% within 5 years. (ADA, 2026)
- Stage 3: diabetes by standard criteria, explained on A1C and blood sugar test results. (ADA, 2026)
What 1 versus 2 or more autoantibodies mean
- Two or more: the persistent presence of two or more islet autoantibodies is a near-certain predictor of clinical diabetes, according to prospective studies. (ADA, 2026) In three cohorts from Finland, Germany and the US, of 585 children who developed more than two autoantibodies, nearly 70% developed type 1 diabetes within 10 years and 84% within 15 years. (ADA, 2026)
- One: in several cohort studies, up to 50% of children with only a single autoantibody become autoantibody negative again during follow-up. (ADA, 2026) Among children with a persistent single autoantibody, the 10-year risk of clinical type 1 diabetes is about 14% to 15%, with much of the risk in the first 2 years. In adults, risk is lower and decreases with age. (ADA, 2026)
- A single IA-2 autoantibody: should be monitored like multiple autoantibodies, because IA-2 positivity is an independent risk factor for progression. (ADA, 2026)
Confirming and monitoring a positive result
- Confirm: the ADA recommends confirming the first positive test with a second test within 3 months, preferably in a laboratory that meets the performance standards of the Islet Autoantibody Standardization Program. (ADA, 2026)
- Check for stage 3 promptly: anyone with one or more positive autoantibodies should be evaluated for stage 3 type 1 diabetes using A1C, urinalysis and/or plasma glucose (recommendation 2.8a). (ADA, 2026)
- Multiple confirmed autoantibodies: referral to a specialized center for metabolic staging, education, and consideration of prevention trials or approved treatments (recommendation 2.8b). (ADA, 2026) People who test positive should be given or referred for counseling about the risk of diabetes, diabetes symptoms and preventing DKA. (ADA, 2026)
- Single confirmed autoantibody: repeat antibody testing every 6 months to 3 years, depending on age, to see whether it persists or more appear (recommendation 2.9). (ADA, 2026)
For a single autoantibody, the ADA describes repeating the four autoantibodies, a random blood glucose and an A1C at these intervals: (ADA, 2026)
- Children 3 years old or younger: every 6 months for 3 years, then once a year for 3 more years.
- Children and adolescents 3 to 18 years old: once a year, and consider stopping after 3 years if there is no progression to multiple antibodies and no dysglycemia.
- Adults: every 3 years, or once a year if there are additional risk factors such as another autoimmune disease, an elevated genetic risk score or a first-degree relative with type 1 diabetes.
Signs to report
Symptoms of type 1 diabetes may include increased urination, feeling very thirsty, feeling very hungry even after eating, blurred vision, fatigue, sores that don't heal, frequent infections and unexplained weight loss. They usually develop quickly, over a few days or weeks. (NIDDK, 2025) The first symptoms can be symptoms of DKA, especially in children: feeling very tired, having trouble breathing, having fruity-smelling breath, fainting from dehydration, or pain in the abdomen, nausea or vomiting. (NIDDK, 2025)
MedlinePlus, when to contact a medical professional (written for people who have type 1 diabetes): (MedlinePlus, type 1 diabetes)
Call 911 or the local emergency number if you have:
- Chest pain or pressure, shortness of breath, or other signs of angina
- Loss of consciousness
- Seizures
- Shortness of breath
- Red, painful skin that is spreading quickly
Contact your provider or go to the emergency room if you have symptoms of diabetic ketoacidosis.
Also contact your provider if you have:
- Blood sugar levels that are higher than the goals you and your provider have set
- Numbness, tingling, or pain in your feet or legs
- Problems with your eyesight
- Sores or infections on your feet
- Frequent feelings of depression or anxiety
- Symptoms that your blood sugar is getting too low (weakness or fatigue, trembling, sweating, irritability, trouble thinking clearly, fast heartbeat, double or blurry vision, uneasy feeling)
- Symptoms that your blood sugar is too high (thirst, blurry vision, dry skin, weakness or fatigue, need to urinate a lot)
- Blood sugar readings that are below 70 mg/dL (3.9 mmol/L)
Where they differ:
- ADA (US, 2026): offer autoantibody screening to people with a family history of type 1 diabetes or otherwise known elevated genetic risk (grade B). (ADA, 2026)
- MedlinePlus: "There is no screening test for type 1 diabetes in people who have no symptoms. However, antibody testing can identify people at higher risk of developing type 1 diabetes if they have first-degree relatives (sibling, parent) with type 1 diabetes or if you have symptoms and would like further testing." (MedlinePlus, type 1 diabetes)
- NICE (UK): its autoantibody recommendations are about diagnosis. For adults with an initial diagnosis of type 1 diabetes, NICE says to measure diabetes-specific autoantibodies; the false negative rate is lowest at diagnosis and can be reduced by testing for 2 different autoantibodies. (NICE NG17) For children and young people, NICE says not to measure diabetes-specific autoantibody titres at initial presentation to distinguish type 1 from type 2 diabetes. (NICE NG18)
- USPSTF (US, 2021): its diabetes recommendation is screening for prediabetes and type 2 diabetes in adults aged 35 to 70 who have overweight or obesity (grade B). It does not address islet autoantibody screening. (USPSTF, 2021)
- Adults with diabetes of unclear type: the ADA recommends standardized islet autoantibody tests to classify diabetes in adults with features that overlap with type 1, such as younger age at diagnosis, unintentional weight loss, ketoacidosis or a short time to insulin treatment (recommendation 2.10). (ADA, 2026)
Your doctor decides what your result means for you.
This page does not give treatment advice, including on medicines or prevention studies. If you have a positive result, see after an abnormal screening result for questions to ask.
Questions people ask
Who should get type 1 diabetes autoantibody screening?
The ADA says autoantibody-based screening for presymptomatic type 1 diabetes should be offered to people with a family history of type 1 diabetes or otherwise known elevated genetic risk. NIDDK says that if you have a parent or sibling with type 1 diabetes, your health care professional may suggest the test even if you have no symptoms. (ADA, 2026) (NIDDK, 2025)
Which autoantibodies are tested?
The ADA lists autoantibodies against insulin, glutamic acid decarboxylase (GAD), islet antigen 2 (IA-2) and zinc transporter 8 (ZnT8). (ADA, 2026)
What does one positive autoantibody mean?
The ADA recommends confirming the first positive test with a second test within 3 months, because up to 50% of children with only a single autoantibody become negative again during follow-up in several cohort studies. A single confirmed autoantibody is retested every 6 months to 3 years, depending on age. A single confirmed IA-2 autoantibody is monitored like multiple autoantibodies. (ADA, 2026)
What does stage 1 type 1 diabetes mean?
Stage 1 means two or more islet autoantibodies with normal blood sugar and no symptoms. The ADA gives a 5-year risk of symptomatic type 1 diabetes of about 44% at stage 1, varying with the number, level and type of autoantibodies, age and genetic risk. (ADA, 2026)
What is TrialNet?
NIDDK describes TrialNet as a research network that offers autoantibody testing to some family members of people with type 1 diabetes. Some people at risk may be able to take part in TrialNet studies. (NIDDK, 2025)