DIDMOAD or Wolfram syndrome is a hereditary disorder characterized by early onset diabetes and optic atrophy. Besides these features, a variety of other symptoms have been described including psychiatrical abnormalities leading to hospitalization in about 25% of all patients. To our knowledge, until now, a detailed characterization of these psychiatric symptoms does not exist. Here we describe a 21-year-old male patient with deficits of frontal lobe function, such as impaired impulse control and learning deficits. Magnetic resonance imaging (MRI) of the brain showed a bilateral optic atrophy, but no signs of frontal brain atrophy. Neuropsychological tests revealed performance deficits in complex planning (e.g., Tower of London). Also his capacities in memorizing logically connected information after a short and delayed period of time were significantly reduced. Since histopathological studies did not reveal frontal brain abnormalities, but did show thalamic neuronal loss and gliosis, we interpret our findings as representative of thalamic dysfunction. In addition, hypoglycaemia seemed to trigger rapid mood swings. As soon as blood glucose levels improved, the patient stabilized emotionally and assaultive behaviour disappeared while the cognitive deficits remained unchanged.