A clinically-employed anti-hyperlipidemic drug, bezafibrate, has been characterized as a peroxisome proliferator-activated receptor (PPAR) pan(, and )-agonist in vitro. Recent extended trials have highlighted its anti-diabetic properties in humans. However, underlying molecular mechanism is not fully elucidated. The present study was designed to explore potential regulatory mechanism of intracellular glucocorticoid reactivating enzyme, 11-hydroxysteroid dehydrogenase type 1 (11-HSD1) and anti-diabetic hormone, adiponectin by bezafibrate in murine adipose tissue and cultured adipocytes. Treatment of db/db mice with bezafibrate significantly ameliorated hyperglycemia and insulin resistance accompanied by a marked reduction of triglyceride and non-esterified fatty acids. Despite equipotent in lipid-lowering effects, another fibrate, fenofibrate did not show such beneficial effects on glycemic control. Treatment of bezafibrate caused a marked decrease in the mRNA level of 11-HSD1 preferentially in adipose tissue of db/db mice (-47%, P<0.05), concomitant with a significant increase in plasma adiponectin level (+37%, P<0.01). Notably, treatment of bezafibrate caused a marked decrease in the mRNA level (-34%, P<0.01) and enzyme activity (-32%, P<0.01) of 11-HSD1, and the treatment substantially augmented the expression (+71%, P<0.01) and secretion (+27%, P<0.01) of adiponectin in 3T3-L1 adipocytes. Knockdown of 11-HSD1 by siRNA confirmed that 11-HSD1 acts as distinct oxo-reductase in adipocytes and validated the enzyme activity assays in the present study. Effects of bezafibrate on regulation of 11-HSD1 and adiponectin in murine adipocytes were comparable to those in thiazolidinediones. This is the first demonstration that bezafibrate directly regulates 11-HSD1 and adiponectin in murine adipocytes, both of which may contribute to metabolically-beneficial effects by bezafibrate.