Abstract
Type 1 diabetes can occur at any age from infancy to elderhood. Patients with hyperglycemia onset at older ages are presumed to have type 2 diabetes. We discuss the case of a 58-year-old man who presented with diabetic ketoacidosis (DKA) at age 51 but was given the diagnosis of type 2 diabetes. During two subsequent admissions for DKA, he suffered severe complications. After his third episode of DKA, antibodies and C-peptide were checked, prompting a change in diagnosis to T1DM. Following a correct diagnosis of T1DM, diabetes education and appropriate treatment, the patient remained free of DKA and had improved glucose control. Under-diagnosis of type 1 diabetes can lead to recurrence of life-threatening episodes of DKA. Anti-GAD antibody and C-peptide testing are under-utilized in the differential diagnosis of type 1 versus type 2 diabetes in adults. The correct diagnosis is necessary to prevent hospital readmissions, morbidity, mortality and medical errors.