Adequately Adapted Insulin Secretion and Decreased Hepatic Insulin Extraction Cause Elevated Insulin Concentrations in Insulin Resistant Non-diabetic Adrenal Incidentaloma Patients
Overview
Affiliations
Background: Insulin-resistance is commonly found in adrenal incidentaloma (AI) patients. However, little is known about beta-cell secretion in AI, because comparisons are difficult, since beta-cell-function varies with altered insulin-sensitivity.
Objectives: To retrospectively analyze beta-cell function in non-diabetic AI, compared to healthy controls (CON).
Methods: AI (n=217, 34%males, 57 ± 1 years, body-mass-index:27.7 ± 0.3 kg/m(2)) and CON [n = 25, 32%males, 56 ± 1 years, 26.7 ± 0.8 kg/m(2)] with comparable anthropometry (p ≥ 0.31) underwent oral-glucose-tolerance-tests (OGTTs) with glucose, insulin, and C-peptide measurements. 1mg-dexamethasone-suppression-tests were performed in AI. AI were divided according to post-dexamethasone-suppression-test cortisol-thresholds of 1.8 and 5 µg/dL into 3 subgroups: pDexa<1.8 µg/dL, pDexa1.8-5 µg/dL and pDexa>5 µg/dL. Using mathematical modeling, whole-body insulin-sensitivity [Clamp-like-Index (CLIX)], insulinogenic Index, Disposition Index, Adaptation Index, and hepatic insulin extraction were calculated.
Results: CLIX was lower in AI combined (4.9 ± 0.2 mg · kg(-1) · min(-1)), pDexa<1.8 µg/dL (4.9 ± 0.3) and pDexa1.8-5 µg/dL (4.7 ± 0.3, p<0.04 vs.CON:6.7 ± 0.4). Insulinogenic and Disposition Indexes were 35%-97% higher in AI and each subgroup (p<0.008 vs.CON), whereas C-peptide-derived Adaptation Index, compensating for insulin-resistance, was comparable between AI, subgroups, and CON. Mathematical estimation of insulin-derived (insulinogenic and Disposition) Indexes from associations to insulin-sensitivity in CON revealed that AI-subgroups had ~19%-32% higher insulin-secretion than expectable. These insulin-secretion-index differences negatively (r=-0.45, p<0.001) correlated with hepatic insulin extraction, which was 13-16% lower in AI and subgroups (p<0.003 vs.CON).
Conclusions: AI-patients show insulin-resistance, but adequately adapted insulin secretion with higher insulin concentrations during an OGTT, because of decreased hepatic insulin extraction; this finding affects all AI-patients, regardless of dexamethasone-suppression-test outcome.
Favero V, Parazzoli C, Bernasconi D, Chiodini I J Endocrinol Invest. 2024; 47(12):2929-2942.
PMID: 39347906 PMC: 11549128. DOI: 10.1007/s40618-024-02440-0.
Antoniotti V, Amore M, Caputo M, Fania C, Mancioppi V, Casoli G J Endocr Soc. 2023; 7(8):bvad088.
PMID: 37424701 PMC: 10326241. DOI: 10.1210/jendso/bvad088.
Wolf P, Dormoy A, Maione L, Salenave S, Young J, Kamenicky P Endocr Connect. 2022; 11(12).
PMID: 36269605 PMC: 9716376. DOI: 10.1530/EC-22-0296.
Athanasouli F, Georgiopoulos G, Asonitis N, Petychaki F, Savelli A, Panou E Endocrine. 2021; 74(1):50-60.
PMID: 33963515 DOI: 10.1007/s12020-021-02741-x.
C-Peptide-based assessment of insulin secretion in the Zucker Fatty rat: a modelistic study.
Di Nardo F, Cogo C, Faelli E, Morettini M, Burattini L, Ruggeri P PLoS One. 2015; 10(5):e0125252.
PMID: 25938808 PMC: 4418729. DOI: 10.1371/journal.pone.0125252.