Screening of Cushing's Syndrome in Outpatients with Type 2 Diabetes: Results of a Prospective Multicentric Study in Italy

Context: Cushing's syndrome may remain unrecognized among patients referred for metabolic syndrome; thus, a proactive screening has been suggested in certain patient populations with features of the disorder. However, conflicting data have been reported on the prevalence of Cushing's syndrome in patients with type 2 diabetes. Objective: Our aim was to evaluate the prevalence of unsuspected Cushing's syndrome among outpatients with type 2 diabetes. Design and Setting: This was a cross-sectional prospective study in 24 diabetes clinics across Italy. Patients: Between June 2006 and April 2008, 813 patients with known type 2 diabetes without clinically overt hypercortisolism were evaluated. Follow-up of the study was closed in September 2010. Patients were not selected for characteristics conferring a higher pretest probability of hypercortisolism. Patients underwent a first screening step with the 1-mg overnight dexamethasone suppression test. Results: Forty patients failed to suppress serum cortisol less th...