Nonalcoholic Steatohepatitis (NASH) is an emerging field. The disease is caused by excessive fat accumulation in the liver called steatosis. This steatosis is linked to the diseases characteristic inflammation, which then potentially leads to progressive fibrosis (the thickening and scarring of connective tissue) and cirrhosis (chronic liver damage).  
Since the pathology of NASH is thought to be significantly driven by the metabolic dysfunction associated with diabetes and obesity.