Clinical characteristics and disease progression of typical adult‐onset type 1 diabetes and insulin‐dependent latent autoimmune diabetes in adults

ABSTRACT Aims We investigated the characteristics of typical adult‐onset type 1 diabetes (T1D) and insulin‐dependent latent autoimmune diabetes in adults (LADA) in Thailand. Methods This retrospective chart review enrolled typical T1D and insulin‐dependent LADA patients diagnosed at age ≥30 years, and who were followed up at Siriraj Hospital, Thailand, during 2014–August 2024. Potential patients were searched from the Type 1 Diabetes Registry of Siriraj Diabetes Center and electronic medical record. Results Among 84 patients, 32 were typical T1D and 52 LADA. At diagnosis, both groups had normal body mass index (20.9 ± 4.5 kg/m 2 ), significant weight loss (13.3 ± 6.4%), short duration of hyperglycemic symptoms (1 [1–2] months), and high fasting blood glucose (259 [174–345] mg/dL). Diabetic ketoacidosis (DKA) was the first presentation in 76.7% of typical T1D and in 2.6% of LADA. Anti‐glutamic acid decarboxylase (anti‐GAD) was tested in 91.7% of patients (positive: T1D 72%, LADA 100%). Almost 70% of patients with LADA were initially misdiagnosed as T2D and were ultimately diagnosed at 7.6 [2.6–17.5] years later. Patients with LADA had a higher incidence of recurrent DKA. At latest follow‐up, patients with LADA had significantly higher systolic blood pressure (SBP), glycated hemoglobin (HbA 1c ), and insulin resistance compared to typical T1D. Conclusions We found a higher proportion of LADA than typical T1D, and 70% of LADA were initially misdiagnosed as T2D. Both groups were characterized by a normal BMI, significant weight loss, and a short duration of hyperglycemic symptoms. However, LADA rarely presented with DKA and had higher HbA 1c and insulin resistance during follow‐up.