Latent Autoimmune Diabetes in Adults: Diagnostic and Therapeutic Challenges

Latent autoimmune diabetes in adults (LADA) represents a distinct form of autoimmune diabetes that manifests in adulthood and is often misdiagnosed as type 2 diabetes mellitus (T2DM). It is characterized by autoimmune destruction of pancreatic β-cells, the presence of circulating autoantibodies, and a gradual but inevitable progression to insulin dependence. This hybrid phenotype combines features of both type 1 and type 2 diabetes, resulting in frequent diagnostic delays and suboptimal management. We report the case of a 36-year-old non-obese male who initially presented with symptomatic hyperglycemia and was treated as T2DM with oral hypoglycemic agents. Despite adherence to metformin and glimepiride, his glycemic control worsened over the following months. Further evaluation revealed low C-peptide levels and positivity for anti-glutamic acid decarboxylase (GAD65) and islet cell antibodies (ICA), establishing a diagnosis of LADA. He was transitioned to basal-bolus insulin therapy and followed for 18 months, during which he achieved improved metabolic control with HbA1c reduction from 9.2% to 6.9%. This case underscores the clinical importance of distinguishing LADA from classical T2DM. The presence of autoantibodies and low endogenous insulin reserve should alert clinicians to the possibility of autoimmune diabetes. Early insulin initiation is advocated to preserve residual β-cell function and minimize long-term complications. In addition, patient education and individualized therapy are crucial in optimizing outcomes. Awareness of LADA among physicians is critical, especially in young and middle-aged adults with atypical features of T2DM, such as lean body habitus, rapid glycemic deterioration, or poor response to oral therapy. This case adds to the growing body of evidence supporting the role of antibody testing and C-peptide assessment in adult-onset diabetes, facilitating accurate classification and timely therapeutic intervention.