How Type 1 Is Diagnosed
Reviewed by CDE Mehandi Sharma · Updated
Diagnosing diabetes and diagnosing which type it is are two separate steps, and the second one matters enormously for treatment.
The first step uses the same tests as any diabetes diagnosis: a blood glucose measurement and an HbA1c, which estimates average blood sugar over the past two to three months. You can see the cut-offs for each test alongside the Type 2 material — they are the same numbers.
The second step is autoantibody testing. This looks for the antibodies left behind when the immune system attacks the insulin-making cells. Their presence is what marks the diabetes as autoimmune, and therefore Type 1.
Ketones are usually checked too, in blood or urine, because a child arriving with high glucose may already be developing ketoacidosis and that changes the urgency completely.
In a young child with rapid symptoms, the diagnosis is often clear enough that treatment starts immediately while confirmatory tests are still running. Insulin is not delayed waiting for an antibody result.
In an adult, the picture is frequently less obvious, and this is exactly where the antibody test earns its place — it is what distinguishes Type 1 from Type 2 when age alone would point the wrong way.