[Same antibodies, new questions: interdisciplinary diagnosis in a 72-year-old female patient with encephalitis]

At 1.5 years after the diagnosis of glutamate decarboxylase(GAD)-associated encephalitis (highly positive GAD antibodies in cerebrospinal fluid and serum) in a 72-year-old patient, hyperglycemia above 40 mmol/l was the cause of progressive neurological symptoms. GAD is an important enzyme in the central nervous system and pancreatic β‑cells that convert L‑glutamate into γ‑aminobutyric acid (GABA). High GAD antibodies are associated with autoimmune diseases such as encephalitis and diabetes mellitus type 1, requiring interdisciplinary diagnostics and therapy.