title: Intramyocellular lipid and insulin resistance: differential relationships in European and African Americans.
abstract: Insulin resistance has been associated with the accumulation of fat within skeletal muscle fibers as intramyocellular lipid (IMCL). Here, we have examined in a cross-sectional study the interrelationships among IMCL, insulin sensitivity, and adiposity in European Americans (EAs) and African Americans (AAs). In 43 EA and 43 AA subjects, we measured soleus IMCL content with proton-magnetic resonance spectroscopy, insulin sensitivity with hyperinsulinemic-euglycemic clamp, and body composition with dual-energy X-ray absorptiometry. The AA and EA subgroups had similar IMCL content, insulin sensitivity, and percent fat, but only in EA was IMCL correlated with insulin sensitivity (r = -0.47, P < 0.01), BMI (r = 0.56, P < 0.01), percent fat (r = 0.35, P < 0.05), trunk fat (r = 0.47, P < 0.01), leg fat (r = 0.40, P < 0.05), and waist and hip circumferences (r = 0.54 and 0.55, respectively, P < 0.01). In a multiple regression model including IMCL, race, and a race by IMCL interaction, the interaction was found to be a significant predictor (t = 1.69, DF = 1, P = 0.0422). IMCL is related to insulin sensitivity and adiposity in EA but not in AA, suggesting that IMCL may not function as a pathophysiological factor in individuals of African descent. These results highlight ethnic differences in the determinants of insulin sensitivity and in the pathogenesis of the metabolic syndrome trait cluster.
authors: Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA. khingram@uab.edu
authors: Katherine H
authors: KH
authors: Ingram
authors: Cristina
authors: C
authors: Lara-Castro
authors: Barbara A
authors: BA
authors: Gower
authors: Robert
authors: R
authors: Makowsky
authors: David B
authors: DB
authors: Allison
authors: Bradley R
authors: BR
authors: Newcomer
authors: A Julian
authors: AJ
authors: Munoz
authors: T Mark
authors: TM
authors: Beasley
authors: Jeannine C
authors: JC
authors: Lawrence
authors: Robert
authors: R
authors: Lopez-Ben
authors: Dana Y
authors: DY
authors: Rigsby
authors: W Timothy
authors: WT
authors: Garvey
mesh_terms: D050153:Abdominal Fat / Q000473:pathology; D015502:Absorptiometry, Photon; D050154:Adiposity / Q000208:ethnology; D000328:Adult; D001741:Black or African American; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology*; D050356:Lipid Metabolism; D009682:Magnetic Resonance Spectroscopy; D024821:Metabolic Syndrome / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000208:ethnology / Q000209:etiology / Q000378:metabolism; D056128:Obesity, Abdominal / Q000208:ethnology* / Q000209:etiology / Q000378:metabolism; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D044465:White People; D055815:Young Adult