Nonalcoholic steatohepatitis (NASH) is a common chronic
liver disease for which there is no known effective
therapy. A proportion of patients with NASH progress to advanced
fibrosis and
cirrhosis. NASH is considered one of the clinical features of the
metabolic syndrome in which
insulin resistance plays a central role. This prospective study evaluates the role of
insulin-sensitizing agent in treatment of NASH. Eighteen nondiabetic patients with biopsy-proven NASH were treated with
pioglitazone (30 mg daily) for 48 weeks. Tests of
insulin sensitivity and body composition as well as liver biopsies were performed before and at the end of treatment. By 48 weeks, serum
alanine aminotransferase values fell to normal in 72% of patients. Hepatic fat content and size as determined by magnetic resonance imaging decreased, and
glucose and
free fatty acid sensitivity to
insulin were uniformly improved. Histological features of steatosis, cellular injury, parenchymal
inflammation, Mallory bodies, and
fibrosis were significantly improved from baseline (all P < 0.05). Using strict criteria, histological improvement occurred in two-thirds of patients.
Pioglitazone was well tolerated; the main side effects were
weight gain (averaging 4%) and an increase in total body adiposity. In conclusion, these results indicate that treatment with an
insulin-sensitizing agent can lead to improvement in biochemical and histological features of NASH and support the role of
insulin resistance in the pathogenesis of this disease. The long-term safety and benefits of
pioglitazone require further study.