Evaluation of the DPP-4 Inhibitor Sitagliptin in the Treatment of Non-Alcoholic Fatty Liver Disease Using MRI

Participants will be persons with type 2 diabetes who are likely to have fatty liver disease. The investigators think that this medication will reduce fatty liver. The investigators will use an MRS (a non invasive method using magnets) to evaluate liver fat before and after subjects take a diabetes medication. The investigators will also collect a small amount of blood to measure liver, kidney and hormone functions. This will be done 4 times. Also, at the time of the subject gets their first dose of medication they will have a DEXA (low exposure x-ray often used in clinical practice to measure bone density and body composition). The goal of all of these studies is to determine whether the study drug lowers liver fat.

Non-alcoholic fatty liver disease (NAFLD) and its progression to non-alcoholic steatohepatitis (NASH) and finally cirrhosis is rapidly becoming the leading cause of liver injury and end stage liver disease, particularly in industrialized countries. Though several pharmacologic agents (i.e. metformin, pioglitazone and others) have been suggested to have benefit in reducing the progression of this disease, none is approved for use. The causes of NAFLD and NASH are unknown, though visceral obesity, metabolic syndrome and type 2 diabetes are recognized co-existent risk factors. Recent evidence has linked NAFLD to elevated dipeptidyl peptidase-4 (DPP-4). DPP-4 levels in the plasma and livers of persons with NAFLD are elevated and correlate with elevations in liver enzymes, though not with markers of insulin resistance alone. It has been proposed that increased DPP-4 activity in combination with decreased PPAR signaling stimulates the inflammatory response that leads to liver fibrosis in the transition of NASH to cirrhosis. Debate exists as to whether the effect of DPP-4 in the liver is via its effect on the intestinal hormones or its direct effects on liver tissue. Indeed some studies have found reductions in liver fat with administration of GLP-1 agonists in animal models of obesity.