Hepatic energy metabolism in human diabetes mellitus, obesity and non-alcoholic fatty liver disease

Alterations of hepatic mitochondrial function have been observed in states of insulin resistance and non-alcoholic fatty liver disease (NAFLD). Patients with overt type 2 diabetes mellitus (T2DM) can exhibit reduction in hepatic adenosine triphosphate (ATP) synthesis and impaired repletion of their hepatic ATP stores upon ATP depletion by fructose. Obesity and NAFLD may also associate with impaired ATP recovery after ATP-depleting challenges and augmented oxidative stress in the liver. On the other hand, patients with obesity or NAFLD can present with upregulated hepatic anaplerotic and oxidative fluxes, including β-oxidation and tricarboxylic cycle activity. The present review focuses on the methods and data on hepatic energy metabolism in various states of human insulin resistance. We propose that the liver can adapt to increased lipid exposition by greater lipid storing and oxidative capacity, resulting in increased oxidative stress, which in turn could deteriorate hepatic mitochondrial function in chronic insulin resistance and NAFLD.