Missed Autoimmune Diabetes: Latent Autoimmune Diabetes in Adults in the Setting of Autoimmune Clustering.

Latent autoimmune diabetes in adults (LADA) is frequently misdiagnosed as type 2 diabetes mellitus (T2DM), particularly in older adults, owing to its adult onset, initial insulin independence, and indolent clinical course, resulting in the delayed initiation of insulin therapy. We present a woman in her sixties with Hashimoto's thyroiditis and a prior diagnosis of Sjögren syndrome who developed progressively worsening hyperglycemia and concurrent rheumatological symptoms, including chronic joint pain and stiffness, despite treatment with multiple noninsulin therapies. Her lean body habitus, absence of clinical insulin resistance, progressive glycemic deterioration, autoimmune background, and musculoskeletal manifestations prompted further evaluation, which revealed markedly elevated pancreatic autoantibodies, including glutamic acid decarboxylase (GAD-65), islet antigen-2 (IA-2), and zinc transporter 8 (ZnT8) antibodies, confirming the diagnosis of LADA with evolving β-cell failure. Transition to insulin-based therapy resulted in excellent glycemic control and was accompanied by substantial improvement in musculoskeletal symptoms, consistent with metabolic rather than inflammatory pathology. This case highlights the importance of recognizing LADA in patients with phenotypic discordance, autoimmune clustering, and systemic manifestations that improve with optimized glycemic control.