ADA and EASD overhaul type 1 diabetes guidelines for adults — here's what changed

Diagnosing type 1 diabetes (T1D) in adults has long been tricky — and a new 2026 consensus report from the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) aims to fix that. The updated guidance, published in both Diabetes Care and Diabetologia, zeroes in on how to accurately differentiate T1D from type 2 diabetes (T2D) in adults with new-onset diabetes, a distinction that's far from straightforward.

The report introduces a clear diagnostic algorithm: test for islet autoantibodies (IAbs) first — two or more positives (or one strongly positive) confirms T1D. If IAbs are negative or borderline, C-peptide levels below 0.6 ng/mL support a T1D diagnosis. The guidance also discourages use of the term "LADA," calling it a confusing label with no universally accepted criteria — it's simply T1D, the authors say.

Key Takeaways:

• ~40% of adults diagnosed with T1D after age 30 are initially misdiagnosed as T2D
• Adults with T1D often have overweight or obesity, so low BMI shouldn't be a prerequisite for suspicion
• New sections cover microvascular complication screening, cardiovascular risk management, and obesity
• C-peptide testing should be interpreted cautiously early in disease course or in patients with severe renal disease

Why it matters: T1D misdiagnosis in adults leads to delayed insulin therapy and worse outcomes. Clearer diagnostic tools and expanded management guidance could meaningfully improve care for a population that's often overlooked.