Type 1 diabetes is one of the most common chronic diseases in children,1 driven by an autoimmune process in which the body’s immune system attacks and destroys the insulin-producing cells of the pancreas. This attack can be detected through blood tests for islet autoantibodies, which are proteins that indicate the immune system is targeting the pancreas. The American Diabetes Association (ADA) began recommending measuring the four of these autoantibodies (GAD65, IA-2, insulin, and ZnT8) in 2025 to confirm an autoimmune cause and distinguish type 1 diabetes from other forms.2,3 Confirming the autoimmune basis of diabetes matters because treatment and monitoring differ by diabetes type, and because an estimated 10–15% of children clinically diagnosed with type 1 diabetes test negative for all measured autoantibodies, a result that can prompt evaluation for monogenic or other non-autoimmune diabetes.4 Confirming autoimmune status is increasingly important as teplizumab has been approved to delay the progression from early-stage type 1 to clinical type 1 diabetes in autoantibody-positive individuals.5 Despite the clinical value of autoantibody testing, real-world testing practices might vary, and the extent to which children newly diagnosed with type 1 diabetes receive this workup is not well described.
We studied 68,439 children newly diagnosed with type 1 diabetes between January 2017 and December 2025. We measured how often the four ADA-recommended autoantibodies plus islet cell antibodies, an older test, were tested in the six months before and after diagnosis, the share of tests that were positive, and the number of positive autoantibodies per child.
Of the children studied, 48.8% had at least one autoantibody test in the six months before through six months after diagnosis, while 51.2% were never tested for any autoantibody. Among those who were tested, 70.1% had at least one positive result and 44.3% were positive for two or more autoantibodies. Because treatment and monitoring differ by diabetes type, the children without a confirmed autoimmune basis for their diagnoses represent a meaningful gap in the diagnostic workup.5
Among autoantibody tests performed for children diagnosed in 2025, positivity varied by type. GAD65 had the highest positivity rate at 61.7%, followed closely by ZnT8 at 60.6% and IA-2 at 56.1%. Islet cell antibodies were positive in 31.4% of tests and insulin autoantibodies in 24.3%. Indeterminate results occurred among 13.7% of insulin autoantibody tests, which might reflect known challenges with insulin autoantibody assay standardization.6 These patterns underscore the importance of testing for multiple autoantibodies because no single test identifies every child with autoimmune diabetes.
Autoantibody testing has risen over time, both before and after diagnosis. Before diagnosis, testing remains uncommon but is trending upward across all five autoantibodies. In 2017, 2.4% of children were tested for GAD65 before their type 1 diabetes diagnosis; by 2025, that share had nearly doubled to 4.2%. Insulin autoantibody testing before diagnosis grew from 1.9% to 3.6%, IA-2 from 1.2% to 3.1%, ZnT8 from 0.4% to 3.3%, and pancreatic islet cell antibodies from 0.8% to 1.9% over the same period. These rising pre-diagnosis testing rates may reflect growing awareness of type 1 diabetes risk screening programs and the availability of therapies for individuals identified in early disease stages.5
Testing after diagnosis is far more common and has also increased. GAD65 remained the most frequently ordered autoantibody, yet even among children diagnosed in 2025, fewer than half (46.6%) were tested for it after diagnosis, up from 31.2% in 2017. Insulin autoantibody testing rose from 24.9% to 40.4%, IA-2 rose from 22.4% to 36.3%, and islet cell antibodies from 7.6% to 23.3%. ZnT8 testing showed the most dramatic growth, climbing from 3.3% in 2017 to 35.1% by 2025.
