A 45-year-old man with recent history of bizarre behavior is seen by a psychiatrist. On physical examination, the patient appears moderately obese with mild hypeension, facial acne, fat accumulation in the supraclavicular fossae. Laboratory studies demonstrate a neutrophilic leukocytosis, with a decrease lymphocytes and absence of eosinophils. There is a mild hypokalemia and mild metabolic alkalosis. The fasting serum glucose is within the reference range, but OGTT had glucose concentrations > 200 mg/dL. Laboratory studies show free urinary coisol of 156 mg/ 24 hours .Which of the following questions would be of most help in establishing a diagnosis?