A patient diagnosed with new-onset type 1 diabetes and Addison's disease at initial presentation

A previously healthy 17-year-old female presented to the emergency department with complaints of vomiting, shortness of breath, and tachycardia. She was found to have an elevated blood glucose and was admitted for presumed new onset type 1 diabetes mellitus (T1DM). During the admission, she was noted to have frequent episodes of hypoglycemia despite conservative insulin dosing and high urine output with glucosuria, which seemed out of proportion to her glucose levels and fluid status. She also had persistent hyponatremia despite normalization of blood glucose. Further work-up was initiated to investigate alternative or additional diagnoses to explain these atypical findings. Adrenocorticotropic hormone (ACTH) level was elevated, consistent with the diagnosis of Addison's disease, which led to the subsequent diagnosis of autoimmune polyglandular syndrome type II (APS-2). This is one of the first reports in the literature of concurrent diagnosis of T1DM and Addison's disease at initial presentation and demonstrates the importance of not anchoring to one diagnosis.