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β-cell function in black South African women: Associations with insulin clearance and ectopic fat

Article scientifique 2020 Anglais

Résumé

Abstract Background: The role of ectopic fat, insulin secretion and clearance in the preservation of β-cell function in black African women with obesity who typically present with hyperinsulinemia is not clear. We aim to examine the associations between disposition index (DI, an estimate of β-cell function), insulin secretion and clearance and ectopic fat deposition.Methods: This is a cross-sectional study of 43 black South African women (age 20-35 years) with obesity (BMI 30-40 kg/m2) and without type 2 diabetes that measured the following: DI, insulin sensitivity (SI), acute insulin response (AIRg), insulin secretion rate (ISR), hepatic insulin extraction and peripheral insulin clearance (frequently-sampled intravenous glucose tolerance test); pancreatic and hepatic fat, visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (aSAT) volume (magnetic resonance imaging), intramyocellular (IMCL) and extramyocellular fat content (EMCL) (magnetic resonance spectroscopy). Results: DI correlated positively with peripheral insulin clearance before (β 55.80, p=0.002) and after adjusting for hepatic insulin extraction. Higher DI was associated with lower VAT, pancreatic fat and soleus fat, but VAT explained most of the variance in DI (32%). Additionally, higher first phase ISR (p=0.033) and lower hepatic insulin extraction (p=0.022) associated with lower VAT, independent from SI, rather than with ectopic fat. Conclusion: Peripheral insulin clearance emerged as an important correlate of DI, independent from hepatic insulin extraction. However, VAT was the main determinant of a lower DI above ectopic fat depots. Importantly, VAT, but not ectopic fat, was associated with both lower insulin secretion and higher hepatic insulin extraction, independent from SI, and may provide a novel explanation of these findings in black South African women with obesity.

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Smidt, M., Mendham, A., Hauksson, J., Alhamud, A., Stefanovski, D., Hakim, O., Swart, J., Goff, L., Kahn, S., Olsson, T., Goedecke, J. (2020). β-cell function in black South African women: Associations with insulin clearance and ectopic fat. https://doi.org/10.21203/rs.3.rs-35455/v2

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Auteur(s)

Melony Fortuin-de Smidt Amy E. Mendham Jón Hauksson Ali Alhamud Darko Stefanovski Olah Hakim Jeroen Swart Louise M. Goff Steven E. Kahn Tommy Olsson Julia H. Goedecke

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