Yasuharu Tabara1, Michiya Igase2, Isao Saito3, Wataru Nishida4, Katsuhiko Kohara5, Susumu Sakurai6, Ryoichi Kawamura4, Yoko Okada2, Shinichi Hitsumoto7, Hiroshi Onuma3, Tokihisa Nagai2, Yasunori Takata4, Eri Uetani2, Rie Takita2, Tomoko Kido2, Namiko Ochi2, Haruhiko Osawa8, Takeshi Tanigawa3, Tetsuro Miki5. 1. Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan. 2. Department of Geriatric Medicine, Ehime University Graduate School of Medicine, Toon City, Japan. 3. 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. 4. Department of Molecular and Genetic Medicine, Ehime University Graduate School of Medicine, Toon City, Japan. 5. 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. 6. 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. 7. Medical Welfare Support Center, Ehime University Hospital, Toon, Japan. 8. 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.
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). CONCLUSION: 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.
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). CONCLUSION: 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.