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Ethnic differences in beta cell function occur independently of insulin sensitivity and pancreatic fat in black and white men

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Meera Ladwa, Oluwatoyosi Bello, Olah Hakim, Fariba Shojaee-Moradie, Maria Linda Boselli, Geoff Charles-Edwards, Janet Peacock, A. Margot Umpleby, Stephanie A. Amiel, Riccardo C. Bonadonna, Louise M. Goff

Original languageEnglish
Article numbere002034
JournalBMJ Open Diabetes Research and Care
Volume9
Issue number1
DOIs
Published24 Mar 2021

Bibliographical note

Funding Information: Funding This work was funded by a Diabetes UK project grant (14/0004967). Funding Information: JP is supported by the NIHR Biomedical Research Centre based at Guy’s and St Publisher Copyright: © BMJ Publishing Group Limited 2021. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors

Abstract

Introduction It is increasingly recognized that type 2 diabetes (T2D) is a heterogenous disease with ethnic variations. Differences in insulin secretion, insulin resistance and ectopic fat are thought to contribute to these variations. Therefore, we aimed to compare postprandial insulin secretion and the relationships between insulin secretion, insulin sensitivity and pancreatic fat in men of black West African (BA) and white European (WE) ancestry. Research design and methods A cross-sectional, observational study in which 23 WE and 23 BA men with normal glucose tolerance, matched for body mass index, underwent a mixed meal tolerance test with C peptide modeling to measure beta cell insulin secretion, an MRI to quantify intrapancreatic lipid (IPL), and a hyperinsulinemic-euglycemic clamp to measure whole-body insulin sensitivity. Results Postprandial insulin secretion was lower in BA versus WE men following adjustment for insulin sensitivity (estimated marginal means, BA vs WE: 40.5 (95% CI 31.8 to 49.2) × 10 3 vs 56.4 (95% CI 48.9 to 63.8) × 10 3 pmol/m 2 body surface area × 180 min, p=0.008). There was a significantly different relationship by ethnicity between IPL and insulin secretion, with a stronger relationship in WE than in BA (r=0.59 vs r=0.39, interaction p=0.036); however, IPL was not a predictor of insulin secretion in either ethnic group following adjustment for insulin sensitivity. Conclusions Ethnicity is an independent determinant of beta cell function in black and white men. In response to a meal, healthy BA men exhibit lower insulin secretion compared with their WE counterparts for their given insulin sensitivity. Ethnic differences in beta cell function may contribute to the greater risk of T2D in populations of African ancestry.

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