Description

Insulin resistance strongly relates to ectopic lipid deposition in skeletal muscle and the liver, which correlate with insulin resistance. Lipid metabolites accumulating in skeletal muscle and the liver are thought to impair insulin signalling and thereby reduce glucose uptake and glycogen storage. Insulin resistant humans frequently present with decreased mitochondrial function in skeletal muscle which might contribute to lipid accumulation and the development of insulin resistance. Non-alcoholic liver disease (NAFLD) comprise fatty liver, steatohepatitis and cirrhosis. NAFLD correlate with insulin resistance increased risk for cardiovascular diseases, type 2 diabetes and hepatocellular. The mechanisms leading from fatty liver to steatohepatitis and insulin resistance in the liver are yet unclear. Bariatric surgery relates to surgery for the reduction of body weight. Bariatric surgery frequently leads to normalization of glucose tolerance in previously diabetic humans even before the onset of body weight reduction. The underlying mechanisms are yet unclear. In this study we aim to explore the mechanisms underlying the onset of insulin resistance and steatohepatitis in patients with fatty liver and to identify the mechanisms leading to improved glucose tolerance in humans after bariatric surgery. We test the following hypotheses: increased lipid availability leads to (i) increased lipid oxidation and oxidative stress (ii) accumulation of lipid metabolites that impair insulin signalling (iii) bariatric surgery improves insulin sensitivity by increasing lipid oxidation.

This study will contribute to the understanding of NAFLD and will help to identify new targets for the therapy of diabetes.