Nonalcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease for which there is limited therapy available. Insulin sensitizing, anti-inflammatory, and antifibrotic properties of thiazolidinediones support their use in treating NASH. We have evaluated pioglitazone in the treatment of nondiabetic patients with NASH.

We randomized 74 nondiabetic patients (45 men; median age, 54 y) with histologically proven NASH to 12 months of standard diet, exercise, and either placebo or pioglitazone (30 mg/day). Sixty-one patients (30 placebo, 31 pioglitazone) had liver biopsies both at the beginning and the end of the study.

Compared with placebo, pioglitazone therapy was associated with an increase in weight (mean change, −0.55 vs +2.77 kg; P = .04) and a reduction in glucose (+0.4 vs −0.1 mmol/L; P = .02), HbA1c (+0.16% vs −0.18%; P = .006), insulin C peptide level (+42 vs −78 pmol/L; P = .02), alanine aminotransferase level (−10.9 vs −36.2 u/L; P = .009), γ-glutamyltransferase level (−9.4 vs −41.2 u/L; P = .002), and ferritin (−11.3 vs −90.5 μg/L; P = .01). Histologic features including hepatocellular injury (P = .005), Mallory–Denk bodies (P = .004), and fibrosis (P = .05) were reduced in patients treated with pioglitazone compared with those in the placebo group.

Pioglitazone therapy over a 12-month period in nondiabetic subjects with NASH resulted in improvements in metabolic and histologic parameters, most notably liver injury and fibrosis. Larger extended trials are justified to assess the long-term efficacy of pioglitazone in this patient group.