Adrenal incidentalomas are tied to increased risk of diabetes: findings from a prospective study

Abstract Context The frequency of adrenal incidentalomas and their association with comorbid conditions have been assessed mostly in retrospective studies that may be prone to ascertainment bias. Objective To evaluate the frequency of adrenal incidentalomas and their associated comorbid conditions. Design Prospective cohort study. Setting Radiology Department at a public hospital. Partecipants Unselected outpatients who underwent an abdominal CT from January 2017 to June 2018. Patients with known or suspected adrenal disease or malignancy were excluded. Exposure All abdominal CT scans were evaluated by an experienced radiologist. Hormonal work-up including a 1-mg dexamethasone suppression test was done in patients bearing adrenal incidentalomas. Main outcome and Measure Frequency of adrenal incidentalomas in abdominal CT of unselected patients; frequency of comorbid conditions, and hormonal work-up in patients bearing adrenal incidentalomas. Results We recruited 601 patients and in 7.3% of them an adrenal tumor was found serendipitously. The patients bearing an adrenal incidentaloma had higher BMI (p=0.009) and waist (p=0.007) and were more frequently diabetic (p=0.0038). At multivariate regression analysis, diabetes was significantly associated with the presence of adrenal incidentalomas (p=0.003). Autonomous cortisol secretion was observed in 50% of patients who did not suppress cortisol <50 nmol/L after 1 mg dexamethasone. Conclusions The frequency of adrenal incidentalomas is higher than previously reported. Moreover, adrenal incidentalomas are tied to increased risk of type 2 diabetes. This finding is free from ascertainment bias because patients with adrenal incidentalomas were drawn from a prospective cohort with the same risk of diabetes than the background population.