Understanding Type 1 Diabetes & Screening
T1D develops in stages long before symptoms show. Autoantibody screening may help some families learn about risk earlier. Talk with your clinician about whether testing is right for you.
The three stages
Stage 1
Two or more islet autoantibodies present, blood glucose still normal. No symptoms - but the immune process has already started, and monitoring begins here.
Stage 2
Two or more autoantibodies plus dysglycaemia (abnormal glucose on OGTT or A1C). Still often symptom-free, and the window where early intervention matters most.
Stage 3
Clinical diagnosis: symptoms appear as insulin production falls. Screening ahead of this stage dramatically lowers the risk of presenting in DKA.
Screening for familial risk
Close relatives of someone with T1D have a higher risk than the general population, so screening is often offered to family members. Most new diagnoses still have no family history, so general-population screening is expanding too. Testing is a standard blood draw.
| Marker | What it means |
|---|---|
| GADA | Glutamic acid decarboxylase antibodies - the most common first marker in adults. |
| IA-2A | Insulinoma-associated-2 antibodies - often signals faster progression in children. |
| IAA | Insulin autoantibodies - typically the earliest marker in very young children. |
| ZnT8A | Zinc transporter 8 antibodies - adds sensitivity when other markers are borderline. |
Reading your result: one positive antibody usually means repeat testing later. Two or more means monitoring with your care team, since progression to Stage 3 becomes likely over time. A negative result at one point in life doesn't rule out a later change.
Signs and symptoms to know
- Unusual thirst and frequent urination
- Unexplained weight loss
- Persistent fatigue or irritability
- Blurred vision
- Fruity-smelling breath, nausea, or rapid breathing (urgent)
Clinical resources
Bring these to your next appointment:
- • ADA Standards of Care - screening and staging guidance
- • JDRF/Breakthrough T1D autoantibody screening programmes
- • TrialNet Pathway to Prevention relative screening
- • A printable question list for your endocrinology visit
Educational information only - always confirm testing and results with your clinician.