Immunology and clinical approach to adult-onset type 1 diabetes

Misdiagnosis of type 1 diabetes (T1D) remains a significant clinical concern, often leading to delays in appropriate treatment to prevent its complications. Accurate and timely diagnosis is critical to optimize patient outcomes, yet distinguishing T1D from other forms of diabetes—particularly type 2—can be challenging, especially in adults. This review highlights the importance of precise and accurate diagnostic strategies by focusing on key clinical and biochemical markers, particularly the presence of islet autoantibodies (IAABs) and reduced C-peptide levels, which are indicative of autoimmune β-cell destruction characteristic of T1D. By synthesizing current literature-limited in some areas-, we evaluate diagnostic pathways that leverage these markers to improve diagnostic accuracy. Additionally, we discuss treatment approaches, emphasizing the central role of insulin therapy and the potential use of adjunctive therapies to enhance glycemic control. This review aims to provide clinicians with practical guidance to refine diagnosis and management of T1D, ultimately reducing the burden of misdiagnosis and improving long-term outcomes.