Subclinical Cushing's syndrome (SCS) is increasingly being reported in incidentally discovered adrenal adenomas; its hallmark is mild autonomous cortisol hyperproduction without specific clinical signs of cortisol excess. Increased prevalence of hypertension, obesity, and impaired glucose tolerance have been described in SCS, but there is no specific study of the risk factors for cardiovascular diseases. In this cross-sectional study we assessed the cardiovascular profile in 28 consecutive SCS patients (19 women and 9 men; aged 56 +/- 10.6 yr) compared with 100 controls matched for age, gender, and body mass index. Systolic (P < 0.001) and diastolic (P < 0.005) blood pressures were higher in patients, as were fasting glucose, insulin, total cholesterol, triglycerides (all P < 0.001), and fibrinogen (P < 0.05). Moreover, the insulin resistance index was increased in patients as was the waist to hip ratio and mean carotid artery intima-media thickness (all P < 0.001). Of the patients, 60.7% had arterial hypertension, 71.4% had lipid abnormalities, 28.6% had impaired glucose tolerance, 35.7% type 2 diabetes mellitus, and 53.6% had abnormalities in hemostatic parameters. Atherosclerotic plaques were more frequent in patients (P < 0.0001). Only 4 (14.3%) patients did not have multiple risk factors for cardiovascular events. Six (21.3%) had clinical evidence of cardiovascular disease; another 11 (39.3%) had cardiovascular abnormalities as revealed by ultrasound scanning of carotid arteries and/or electrocardiogram records. These results strongly suggest that an increased cardiovascular risk profile, similar to that described in overt Cushing's syndrome, is present in SCS subjects. This finding supports the concept that chronic mild endogenous cortisol excess may have important systemic effects on the human body.