Double autoimmune endocrinopathies: concurrent presentation of latent autoimmune diabetes in adults and Graves disease.

Latent autoimmune diabetes in adults (LADA) and Graves disease (GD) may coexist due to shared autoimmune mechanisms and genetic susceptibility. We report a 39-year-old woman with class III obesity who presented with palpitations, blurry vision, and hypertension. Evaluation revealed new-onset diabetes (hemoglobin A1c 8.3% [SI: 67 mmol/mol]; reference range, 4.6-6.4% [SI: 27-46 mmol/mol]) and hyperthyroidism with suppressed thyroid stimulating hormone and elevated free thyroxine (free T4), along with positive thyroid peroxidase and thyrotropin receptor antibodies, confirming GD. Further testing demonstrated markedly elevated glutamic acid decarboxylase-65, zinc transporter 8, and insulinoma-associated antigen-2 antibodies. C-peptide was 2.34 ng/mL (SI: 0.78 nmol/L) (reference range, 0.80-3.85 ng/mL [SI: 0.26-1.27 nmol/L]) with a glucose of 92 mg/dL (SI: 5.1 mmol/L) (reference range, 70-99 mg/dL [SI: 3.9-5.5 mmol/L]), consistent with early LADA. She was treated with methimazole and metformin as she was quite averse to insulin therapy and was able to achieve good glycemic control. At 23 months, worsening hyperglycemia with declining C-peptide level, necessitated multiple daily insulin injections and continuous glucose monitoring. This case highlights the biphasic course of LADA and the importance of screening for additional autoimmune diseases, consistent with autoimmune polyglandular syndrome type 3.