ICIs are associated with immune-related adverse events including autoimmune encephalitis, although both paraneoplastic phenomena and ICI treatment may lead to autoimmunity.<h4>Case presentation</h4>We describe a 72-year old male patient with small-cell lung cancer, who during adjuvant treatment with Durvalumab developed GABA<sub>B</sub>R<sub>1</sub> and GAD65 antibodies and both diabetes and autoimmune limbic encephalitis. Here, GAD2 is linked to diabetes mellitus.