Mistaken Identity: Missed Diagnosis of Type 1 Diabetes in an Older Adult.

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, but the misdiagnosis of type 2 diabetes as type 1 diabetes in adults has serious consequences. Medical error in this domain leads to significant patient harm that could be avoided with the correct diagnostic testing. Here, 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. This case demonstrates the consequences of the mis-diagnosis of type 1 diabetes as type 2 diabetes. The correct diagnosis is necessary to prevent hospital readmissions, morbidity, mortality and medical errors.