title: Ethnic differences in hepatic and systemic insulin sensitivity and their associated determinants in obese black and white South African women.
abstract: OBJECTIVE
  There is evidence to suggest that ectopic fat deposition in liver and skeletal muscle may differ between black and white women resulting in organ-specific differences in insulin sensitivity. Accordingly, the aim of the study was to examine ethnic differences in hepatic and peripheral insulin sensitivity, and the association with hepatic and skeletal muscle lipid content, and skeletal muscle gene expression.
  
  
  METHODS
  In a cross-sectional study including 30 obese premenopausal black and white women, body composition (dual energy x-ray absorptiometry), liver fat and skeletal muscle (soleus and tibialis anterior) fat accumulation (proton-magnetic resonance spectroscopy), skeletal muscle gene expression, insulin sensitivity (two-step isotope labelled, hyperinsulinaemic-euglycaemic clamp with 10 mU m(-2) min(-1) and 40 mU m(-2) min(-1) insulin infusions), and serum adipokines were measured.
  
  
  RESULTS
  We found that, although whole-body insulin sensitivity was not different, obese white women presented with lower hepatic insulin sensitivity than black women (% suppression of endogenous glucose production [% supp EGP], median [interquartile range (IQR)]: 17 [5-51] vs 56 [29-100] %, p = 0.002). While liver fat tended to be lower (p = 0.065) and skeletal muscle fat deposition tended to be higher (p = 0.074) in black compared with white women, associations with insulin sensitivity were only observed in black women (% supp EGP vs liver fat: r = -0.57, p < 0.05 and % supp EGP vs soleus fat: r = -0.56, p < 0.05).
  
  
  CONCLUSIONS
  These findings may suggest that black women are more sensitive to the effects of ectopic lipid deposition than white women.
authors.affiliation: Non-Communicable Disease Research Unit, South African Medical Research Council, PO Box 19070, Tygerberg, 7505, South Africa. julia.goedecke@mrc.ac.za.|Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa. julia.goedecke@mrc.ac.za.
authors.forename: Julia H
authors.initials: JH
authors.lastname: Goedecke
authors.affiliation: Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: Dheshnie
authors.initials: D
authors.lastname: Keswell
authors.affiliation: Division of Diabetes and Endocrinology, Department of Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Carsten
authors.initials: C
authors.lastname: Weinreich
authors.affiliation: MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: Jia
authors.initials: J
authors.lastname: Fan
authors.affiliation: Center for Medical Technology and Radiation Physics, Umeå University Hospital, Umeå, Sweden.
authors.forename: Jon
authors.initials: J
authors.lastname: Hauksson
authors.affiliation: Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: Hendriena
authors.initials: H
authors.lastname: Victor
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and University of Washington, Seattle, WA, USA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Utzschneider
authors.affiliation: Division of Diabetes and Endocrinology, Department of Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Levitt
authors.affiliation: Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: Estelle V
authors.initials: EV
authors.lastname: Lambert
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and University of Washington, Seattle, WA, USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Kahn
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.|Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Tommy
authors.initials: T
authors.lastname: Olsson
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D050154:Adiposity / Q000208:ethnology; D000328:Adult; D044383:Black People; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology*; D008099:Liver / Q000378:metabolism*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D009765:Obesity / Q000208:ethnology* / Q000378:metabolism; D017697:Premenopause; D013019:South Africa; D044465:White People
keywords: Black African; Ectopic fat; Ethnicity; Euglycaemic–hyperinsulinaemic clamp; Hepatic insulin sensitivity; Liver fat; Peripheral insulin sensitivity; Skeletal muscle lipid