Endocrine Abstracts

Aim: To evaluate the prevalence and incidence of type 2 diabetes in patients with nonfunctioning adrenal incidentalomas (NFAI) and autonomous cortisol secretion (ACS) coming from a cohort of adrenal incidentalomas consecutively evaluated in a tertiary hospital in a predefined period (2013-2020).

Methods: In this retrospective study, adrenal incidentalomas ≥1cm with ACS and NFAI were included. ACS was defined by a post-dexamethasone suppression test (DST) serum cortisol ≥1.8 μg/dl, in the absence of signs of hypercortisolism, and NFAI as a DST <1.8 μg/dl and no biochemical evidence of other hormonal hypersecretion.

Results: Inclusion criteria were met by 709 patients, 231 with ACS and 478 with NFAI. At the diagnosis of the adrenal incidentaloma, type 2 diabetes was present in in 172 (24.3%) patients, 13 were under treatment only with life-style changes (diet and exercise), 98 with oral antidiabetics, 16 with insulin in monotherapy and 45 with insulin and oral antidiabetic drugs in combination. No difference in its prevalence was found between patients with ACS and NFAI (27.7% vs. 22.6%, P=0.137). Neither in the proportion of type 2 diabetic patients under insulin therapy (33.9% vs. 23.1%, P=0.130). However, fasting plasma glucose and HbA1c levels were significantly higher in patients with ACS than with NFAI (112.3±35.56 vs 105.0±29.05 mg/dl, P=0.004 and 6.5±1.36 vs. 6.1±0.89%, P=0.005, respectively). Furthermore, patients with type 2 diabetes had higher urinary free cortisol (54.8 ±101.52 vs. 38.3±29.08 μg/dl; P=0.039) and late-night salivary cortisol levels (5.0±5.73 vs. 3.5±3.57 μg/dL, P=0.010) than those without type 2 diabetes. After a media follow-up of 28 months [IQR 2.0-125.3], a total of 24 patients developed type 2 diabetes. No differences in incidence were found between patients with ACS and NFAI (HR 1.17, 95% 0.52-2.64).

Conclusion: Type 2 diabetes affects a quarter of patients with adrenal incidentalomas, with no differences in its prevalence and incidence in patients with ACS and NFAI. However, the glycemic control seems to be worse in those who have associated ACS. Also, higher levels of urinary and salivary cortisol are found in patients with type 2 diabetes compared to those without type 2 diabetes.