Aims: Subclinical hypercortisolism was reported to be more prevalent among diabetic, obese and hypertensive patients. Our primary aim was to investigate the prevalence of subclinical hypercortisolism in patients from the Rio de Janeiro Type 2 Diabetes (RIO-T2D) Cohort; and secondarily to assess its associated factors. Methods: From May 2013 to August 2014, 393 diabetic outpatients underwent overnight 1 mg dexamethasone suppression test (DST). Patients with non-suppressive morning cortisol (≥1.8 μg/dl) were further evaluated with nocturnal salivary cortisol, two readings N0.35 μg/dl were considered confirmatory for subclinical hypercortisolism. Results: One-hundred twenty-eight patients (32.6%) failed to suppress morning cortisol, and in 33 patients (8.6%) subclinical hypercortisolism was confirmed. Independent correlates of a positive DST were older age (OR: 1.04; 95% CI: 1.01–1.07; p = 0.007), number of anti-hypertensive drugs in use (OR: 1.26; 95% CI: 1.05–1.50; p = 0.012), longer diabetes duration (OR: 1.03; 95% CI: 1.004–1.06; p = 0.023), and presence of diabetic nephropathy (OR: 1.70; 95% CI:1.01–2.87; p = 0.047). Independent correlates of confirmed subclinical hypercortisolism were a greater number of anti-hypertensive medications (OR: 1.54; 95% CI:1.14–2.06; p = 0.004), shorter diabetes duration (OR: 0.92; 95% CI: 0.87–0.98; p = 0.006), and increased aortic stiffness (OR: 2.81; 95% CI: 1.20–6.57; p = 0.017); metformin use was protective (OR: 0.27; 95% CI: 0.10–0.73; p = 0.010). Conclusion: Patients with type 2 diabetes had a high prevalence of subclinical hypercortisolism, and its presence was associated with more severe hypertension and increased aortic stiffness.