Reduced insulin effect in subclinical fatty liver

Abstract

Steatosis of the liver is known to be associated with impaired insulin action and is considered to be a feature of the metabolic syndrome. In the present study we addressed the question whether liver fat content, as measured by proton MR spectroscopy ( (1)H MRS), in healthy subjects without clinical signs (hepatomegaly, elevation of transaminases) of relevant liver disease correlates with whole-body insulin sensitivity. 21 (18 males and 3 females, age 35 +/- 11 years) non-diabetic subjects underwent the euglycemic-hyperinsulinemic clamp test for determination of whole body insulin action. Liver fat content was measured by means of proton MR spectroscopy ( (1)H MRS). Lipid content was calculated as percentage share of the lipid signal in relation to the entire signal of the spectrum (water and lipid signals). Clinically relevant steatosis of the liver was ruled out by standard magnetic resonance imaging (MRI). Subjects with a history of alcohol intake of more than 40 g/d were excluded from analysis. In a single correlation analysis percentage liver fat strongly correlated with insulin sensitivity index (ISI) (r = 0.7, p = 0.001). After adjusting for the effects of percentage body fat (PFAT) percentage liver fat remained an independent determinant of ISI (p = 0.01). Our results suggest that liver fat content is an important predictor of whole-body insulin sensitivity in healthy subjects. The correlation of liver fat content with insulin sensitivity was found in the absence of clinical steatosis and was independent of body fat content.