Liver, visceral and subcutaneous fat in men and women of South Asian and white European descent: a systematic review and meta-analysis of new and published data

Iliodromiti, S. et al. (2023) Liver, visceral and subcutaneous fat in men and women of South Asian and white European descent: a systematic review and meta-analysis of new and published data. Diabetologia, 66(1), pp. 44-56. (doi: 10.1007/s00125-022-05803-5) (PMID:36224274) (PMCID:PMC9729139)

Abstract

Aims/hypothesis: South Asians have a two- to fivefold higher risk of developing type 2 diabetes than those of white European descent. Greater central adiposity and storage of fat in deeper or ectopic depots are potential contributing mechanisms. We collated existing and new data on the amount of subcutaneous (SAT), visceral (VAT) and liver fat in adults of South Asian and white European descent to provide a robust assessment of potential ethnic differences in these factors. Methods: We performed a systematic review of the Embase and PubMed databases from inception to August 2021. Unpublished imaging data were also included. The weighted standardised mean difference (SMD) for each adiposity measure was estimated using random-effects models. The quality of the studies was assessed using the ROBINS-E tool for risk of bias and overall certainty of the evidence was assessed using the GRADE approach. The study was pre-registered with the OSF Registries (https://osf.io/w5bf9). Results: We summarised imaging data on SAT, VAT and liver fat from eight published and three previously unpublished datasets, including a total of 1156 South Asian and 2891 white European men, and 697 South Asian and 2271 white European women. Despite South Asian men having a mean BMI approximately 0.5–0.7 kg/m2 lower than white European men (depending on the comparison), nine studies showed 0.34 SMD (95% CI 0.12, 0.55; I2=83%) more SAT and seven studies showed 0.56 SMD (95% CI 0.14, 0.98; I2=93%) more liver fat, but nine studies had similar VAT (−0.03 SMD; 95% CI −0.24, 0.19; I2=85%) compared with their white European counterparts. South Asian women had an approximately 0.9 kg/m2 lower BMI but 0.31 SMD (95% CI 0.14, 0.48; I2=53%) more liver fat than their white European counterparts in five studies. Subcutaneous fat levels (0.03 SMD; 95% CI −0.17, 0.23; I2=72%) and VAT levels (0.04 SMD; 95% CI −0.16, 0.24; I2=71%) did not differ significantly between ethnic groups in eight studies of women. Conclusions/interpretation: South Asian men and women appear to store more ectopic fat in the liver compared with their white European counterparts with similar BMI levels. Given the emerging understanding of the importance of liver fat in diabetes pathogenesis, these findings help explain the greater diabetes risks in South Asians.

• Item Type: Articles
• Additional Information: The study was partially supported by funding from the European Federation of Pharmaceutical Industries Associations (EFPIA)-Innovative Medicines Initiative (IMI) Joint Undertaking-European Medical Information Framework (EMIF) (grant no. 115372). SI is funded by a Medical Research Council postdoctoral fellowship (MR/N015177/1). The funders had no role in the study design, data collection, data analysis, data interpretation, or writing of the report.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Foster, Dr John and Gill, Professor Jason and Ghouri, Dr Nazim and Lumsden, Professor Mary and Iliodromiti, Dr Stamatina and McLaren, Dr James and Ballantyne, Dr Stuart and Sattar, Professor Naveed
• Authors: Iliodromiti, S., McLaren, J., Ghouri, N., Miller, M. R., Dahlqvist Leinhard, O., Linge, J., Ballantyne, S., Platt, J., Foster, J., Hanvey, S., Gujral, U. P., Kanaya, A., Sattar, N., Lumsden, M. A., and Gill, J. M.R.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health; College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
• Journal Name: Diabetologia
• Publisher: Springer
• ISSN: 0012-186X
• ISSN (Online): 1432-0428
• Published Online: 13 October 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Diabetologia 66(1): 44-56
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
168916		EMIF	Naveed Sattar	European Commission (EC)	115372	Institute of Cardiovascular & Medical Sciences
172631		Women's reproductive health and its relation to diabetes and cardiovascular health	Stamatina Iliodromiti	Medical Research Council (MRC)	MR/N015177/1	Med - Reproductive and Maternal Medicine