title: Nondiabetic patients with either subclinical Cushing's or nonfunctional adrenal incidentalomas have lower insulin sensitivity than healthy controls: clinical implications.
abstract: OBJECTIVE
  The aim of this study was to estimate insulin sensitivity (IS) in nondiabetic patients with adrenal incidentalomas (AI): nonfunctional adrenal incidentalomas (NAI) and patients with AI and subclinical Cushing's syndrome (SCS).
  
  
  METHODS
  Based on the inclusion criteria (normal fasting glucose levels, no previous history of impaired fasting glucose and/or diabetes, and no medications or concomitant relevant diseases) and the exclusion criteria (pheochromocytoma, overt hypercortisolism, hyperaldosteronism, adrenal carcinoma, metastasis of extra-adrenal tumors, extra-adrenal malignancies), 142 subjects were drawn from a series of patients with AI. The subjects were age-, sex- and body mass index (BMI)-matched: 70 with NAI (50 women and 20 men), 37 with AI and SCS (31 women and 6 men) and 35 healthy control (HC) subjects (30 women and 5 men). The oral glucose tolerance test (OGTT) and several indices of insulin sensitivity (IS) were used: homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI), triglycerides and glucose index (TyG), index of whole-body insulin sensitivity (ISI-composite) and glucose to insulin ratio (G/I).
  
  
  RESULTS
  There was a significant difference in IS between subjects with NAI and HC (HOMA, p=0.049; QUICKI, p=0.036; TyG, p=0.002; ISI-composite, p=0.024) and subjects with SCS and HC (AUC insulin, p=0.01; HOMA, p=0.003; QUICKI, p=0.042; TyG, p=0.008; ISI-composite, p=0.002). There was no difference in the tested indices of IS between subjects with NAI and SCS (p>0.05). However, subjects with SCS had a significantly higher prevalence of impaired glucose tolerance and higher area under the curve for glucose than subjects with NAI (p=0.0174). The linear regression analysis showed that 1 mg-DST cannot be used as a predictor of HOMA (R(2)=0.004, F=0.407, p=0.525). Significant relationship was found between 1 mg-DST and ISI-composite (R(2)=0.042, F=4.981, p=0.028) but this relationship was weak and standard error of estimate was high. The linear regression model also showed that ACTH cannot be used as a predictor of HOMA (R(2)=0.001, F=0.005, p=0.943) or ISI-composite (R(2)=0.015, F=1.819, p=0.187).
  
  
  CONCLUSIONS
  Insulin resistance is a major cardiovascular risk factor; therefore, the assessment of IS in patients with AI, even nonfunctional, has a valuable place in the endocrine workup of these patients.
authors: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade.
authors: Miomira
authors: M
authors: Ivović
authors: Ljiljana V
authors: LV
authors: Marina
authors: Svetlana
authors: S
authors: Vujović
authors: Milina
authors: M
authors: Tančić-Gajić
authors: Miloš
authors: M
authors: Stojanović
authors: Nevena V
authors: NV
authors: Radonjić
authors: Milan
authors: M
authors: Gajić
authors: Ivan
authors: I
authors: Soldatović
authors: Dragan
authors: D
authors: Micić
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000378:metabolism*; D016022:Case-Control Studies; D003480:Cushing Syndrome / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D008875:Middle Aged