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 The objective of this work is to evaluate the frequency of adrenal incidentalomas and their associated comorbid conditions. Design A prospective cohort study was conducted. Setting This study took place at a radiology department at a public hospital. Participants Unselected outpatients who underwent an abdominal computed tomography (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 workup including a 1-mg dexamethasone suppression test was performed 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 workup 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 body mass index (P = .009) and waist circumference (P = .004) and were more frequently diabetic (P = .0038). At multivariable regression analysis, diabetes was significantly associated with the presence of adrenal incidentalomas (P = .003). Autonomous cortisol secretion was observed in 50% of patients who did not suppress cortisol less than 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 as the background population.