Hypercortisolism in Newly Diagnosed Type 2 Diabetes: A Prospective Study of 384 Newly Diagnosed Patients

Cross-sectional studies in small and selected populations report a high prevalence of hypercortisolism in patients with type 2 diabetes (T2D), which could have therapeutic implications, if confirmed. We therefore estimated the prevalence of hypercortisolism in a large and unselected cohort of recently diagnosed T2D patients. Consecutive patients with recently diagnosed T2D first underwent an overnight dexamethasone (1 mg) suppression test (OD). Patients not suppressing serum cortisol ≤50 nmol/l proceeded with a 48-h low dose dexamethasone suppression test (LDDST) and 24-h urinary free cortisol collection (UFC). Patients with elevated cortisol levels according to LDDST and/or UFC underwent imaging guided by plasma ACTH levels, and assessment of bone mineral density. A total of 384 T2D patients (232male/152 females) with a mean age of 60±10 years were included. Eighty-five (22%) patients suppressed incompletely to OD of whom 20 (5%) failed to suppress after LDDST and/or had elevated UFC (=hypercortisolism). Patients with hypercortisolism did not differ as regards age, BMI, HbA1c, T-score or blood pressure, but a higher proportion of them received antihypertensive treatment (100% vs. 64%, p=0.001). Imaging revealed adrenal adenoma(s) in 9 cases and a pituitary macroadenoma in 1 case. We found a 5% prevalence of hypercortisolism in unselected, recently diagnosed T2D, which was not associated with a persuasive cushingoid phenotype. The clinical implications are therefore uncertain.