title: Association of hematological parameters with insulin resistance, insulin sensitivity, and asymptomatic cerebrovascular damage: the J-SHIP and Toon Health Study.
abstract: BACKGROUND
  Elevated hematocrit levels have been suggested to be an independent determinant of insulin resistance and type 2 diabetes. To clarify the diagnostic significance of hematocrit level, we investigated the association with hemodynamic profiles, insulin resistance and insulin sensitivity, arterial properties, and asymptomatic cerebrovascular damage in a general Japanese population.
  
  
  METHODS
  This study included 1,978 participants from two independent cohorts. Insulin sensitivity was assessed by the oral 75 g glucose tolerance test. Carotid ultrasonography was performed to evaluate atherosclerosis and wall shear stress. Periventricular hyperintensity and lacunar infarction were assessed by brain magnetic resonance imaging.
  
  
  RESULTS
  Hematocrit quartile showed a stepwise association with insulin sensitivity (Q1: 2.2±0.7, Q2: 2.0±0.7, Q3: 1.9±0.7, Q4: 1.8±0.6, p<0.001) and insulin resistance (1.0±0.6, 1.2±0.7, 1.3±0.8, 1.5±1.0, p<0.001). Multiple linear regression analysis adjusted for possible covariates identified hematocrit as an independent determinant of insulin sensitivity (β=-0.074, p=0.019) and insulin resistance (β=0.115, p<0.001). However, this association was lost after further adjustment for visceral fat area and plasma alanine aminotransferase level. Further, no significant association was observed between hematocrit and carotid intima-media thickness (p=0.306) where as wall shear stress was inversely associated with the carotid atherosclerosis (r=-0.250, p<0.001). In contrast, a low hematocrit level was independently associated with periventricular hyperintensity (odds ratio 0.87 (95% CI 0.80-0.95), p=0.001).
  
  
  CONCLUSIONS
  Hematocrit was positively associated with insulin resistance and insulin sensitivity. This association was epiphenomenon of visceral and hepatic adiposity. Conversely, low hematocrit was a significant risk factor for periventricular hyperintensity independent of insulin resistance.
authors.affiliation: Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Tabara
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Michiya
authors.initials: M
authors.lastname: Igase
authors.affiliation: Department of Public Health, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Saito
authors.affiliation: Department of Molecular and Genetic Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nishida
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kohara
authors.affiliation: Department of Public Health, Ehime University Graduate School of Medicine, Toon City, Japan Department of Clinical Laboratory Science, Faculty of Health Care, Tenri Health Care University, Tenri, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakurai
authors.affiliation: Department of Molecular and Genetic Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Kawamura
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okada
authors.affiliation: Medical Welfare Support Center, Ehime University Hospital, Toon, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hitsumoto
authors.affiliation: Department of Public Health, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Onuma
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Tokihisa
authors.initials: T
authors.lastname: Nagai
authors.affiliation: Department of Molecular and Genetic Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Takata
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Uetani
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Takita
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kido
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan.
authors.forename: Namiko
authors.initials: N
authors.lastname: Ochi
authors.affiliation: Department of Molecular and Genetic Medicine, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Osawa
authors.affiliation: Department of Public Health, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanigawa
authors.affiliation: Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan Division of Anti-aging and Genetics, Ehime University Proteo-Medicine Research Center, Toon City, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Miki
mesh_terms: D000368:Aged; D002340:Carotid Artery Diseases / Q000097:blood* / Q000000981:diagnostic imaging / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D005260:Female; D005951:Glucose Tolerance Test; D006400:Hematocrit; D006439:Hemodynamics; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D012307:Risk Factors; D014463:Ultrasonography
keywords: Hematocrit; atherosclerosis; cerebrovascular disease; insulin resistance