Objective and hypotheses: We describe a five year old boy with AADCdeficiency. Severe, unpredictable, episodes of hypglycaemia were documented when he was switched from bromocryptine to pramipexol, a more potent dopamine agonist, in order to try to improve his motoric disabilities. Episodes of hypoglycaemia are documented in other patients with this disease. The pathogenesis of hypoglycaemia in these patients however is unknown. I hypothezise that a potent dopamine agonist in these patients can give rise to hypoglycaemia based on inhibition of growth hormone secretion through activation of dopanine D2 receptors and/or by the autonomic dysfunction in these patients with virtually no sympathetic activity left.