ABSTRACT
A 67-year-old man was admitted to our hospital because of decreased oral intake and confusion. He had a 2-year history of diabetes mellitus and he had a good glycaemic control with oral antidiabetic drugs (latest HbA1C:7.2%). Quetiapine was initiated 15 days ago in a psychiatric clinic because of depression. The patient was taken to the intensive care unit with the diagnosis of hyperosmolar nonketotic state and acute renal failure. All the medications were discontinued; intravenous hydration and insulin infusion were started. The relationship between second-generation antipsychotics (SGAs) and hyperglycemia is a topic of interest and insulin resistance is commonly accepted as the mechanism for hyperglycemia. Patients receiving SGAs should be followed more closely for metabolic disorders.