Objectives  To explore associations between plasma adiponectin concentrations and liver histology in patients with nonalcoholic fatty liver disease (NAFLD).

Design and patients  In a cross-sectional study, we enrolled 60 consecutive NAFLD patients and 60 age-, sex- and body mass index (BMI)-matched healthy controls.

Measurements  NAFLD (by liver biopsy), plasma adiponectin concentrations, insulin resistance (by homeostasis model assessment, HOMA-IR) and metabolic syndrome (MetS) features.

Results  NAFLD patients had a marked decrease in plasma adiponectin concentration (6·1 ± 2·8 vs. 13·6 ± 3·8 µg/ml, P < 0·001) compared with matched controls. MetS, as defined by the Adult Treatment Panel III (ATP III) criteria, and its individual components were more frequent among NAFLD patients. The marked differences in adiponectin concentrations that were observed between the groups were little affected by adjustment for age, sex, BMI, HOMA-IR score and MetS components. Notably, decreased adiponectin levels were closely associated with the degree of hepatic steatosis, necroinflammation and fibrosis (P < 0·001 for all) among NAFLD patients. By logistic regression analysis, low adiponectin levels independently predicted hepatic steatosis [odds ratio (OR) 2·3, 95% confidence interval (CI) 1·5–5·8, P < 0·001] and necroinflammation (OR 3·1, 95% CI 1·9–7, P < 0·001), but not fibrosis (P = 0·07), after adjustment for age, sex, BMI, HOMA-IR and MetS components.

Conclusions  NAFLD patients have markedly lower plasma adiponectin concentrations than control subjects. Low adiponectin levels are strongly associated with the severity of liver histology, thus further supporting the hypothesis that adiponectin might be involved in the development of NAFLD.