Objective: To determine whether fatty liver impairs insulin clearance and contributes to insulin resistance in obese and lean healthy non-diabetic men and women.
Design: Cross-sectional, descriptive.
Setting: Medical outpatient clinic; university hospital.
Subjects: Twenty-seven (14 men) non-diabetic obese (Body fat % = 31.5 +/- 9.3; mean +/- s.d.) and 19 (13 men) non-diabetic non-obese (body fat % = 19.0 +/- 6.8; P < 0.01 vs obese) healthy subjects aged 31-64 without liver disease.
Major outcome measures: Liver density relative to the spleen on CT scan (LFS), glucose infusion rate (GIR) and metabolic insulin clearance rate (MIC) during euglycemic hyperinsulinemic clamp; anthropometric (waist-hip ratio: WHR) and CT-determined (visceral fat area: VFA) measures of fat distribution.
Results: Fatty liver was inversely related to MIC (r = -0.39; P < 0.01) with a positive correlation with fasting p-insulin (r = 0.39; P < 0.01). There were no statistically significant correlations between BMI, body fat % or WHR and MIC. GIR was inversely related to body fat % (r = -0.49; P < 0.01), VFA (r = -0.56; P < 0.01) and WHR (r = -0.36; P < 0.01) in all subjects, with an inverse relationship to fatty liver in men (r = -0.43; P < 0.05).
Conclusion: Increased steatosis of the liver is associated with reduced insulin clearance, contributing to insulin resistance in non-diabetic Japanese men and women.