A patient in their 50s presented to the emergency department (ED) with complaints of nausea, vomiting, and malaise for 5 days. An initial electrocardiogram (ECG) demonstrated an ectopic atrial rhythm with no other abnormality. The patient was found to have hyperglycemia without evidence of ketoacidosis and was diagnosed with new-onset diabetes mellitus. Prior to discharge, the patient became unresponsive and pulseless. The ED team immediately performed advanced cardiac lifesaving interventions and obtained brief returns of spontaneous circulation. Bolus-dose epinephrine was administered repeatedly for unstable bradydysrhythmia; however, the patient experienced recurrent cardiopulmonary arrests. An interarrest ECG is provided in the Figure, A.