Independent association of liver fat accumulation with insulin resistance

Background: To examine the association of intrahepatic fat with homeostasis model assessment-insulin resistance (HOMA-IR), a marker of insulin resistance, in Japanese adults, and whether intrahepatic fat is associated with insulin resistance independent of waist circumference and other measures of obesity. Methods: Fifty-three individuals aged 37-69 were studied. Spectrum obtained using a 3-T magnetic resonance imager was analysed with LCModel to quantify intrahepatic fat. Blood levels of insulin, glucose and other biochemical markers were obtained after 8 h or more fasting. Percent body fat was estimated by a bioelectrical impedance analyzer. HOMA-IR and intrahepatic fat content were log-transformed in the analysis. Results: We found a positive correlation between intrahepatic fat and HOMA-IR, which was independent of the anthropometric measures of obesity. In contrast, significant and positive correlations of body mass index, percent body fat, and waist circumference with HOMA-IR were largely explained by their associations with intrahepatic fat. Intrahepatic fat was positively associated with alanine transaminase and triglycerides even after adjustment for HOMA-IR. Conclusion: Intrahepatic fat was associated with insulin resistance independent of age, sex, and measures of obesity in Japanese adults. Hypertriglyceridemia and liver injury may directly occur subsequent to intrahepatic fat accumulation.

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