Abstract： Objective To investigate effects of pioglitazone(Pio) on the acute and chronic impairment of insulin secretion (IS) by free fatty acids. MethodsβTC3 cells were divided into control group, FFAs group and FFAs +Pio group, and cultured in vitro for 1h,72h. Insulin releasing test was performed. Insulin level was examined by radioimmunoassay, the mRNA of free fatty acid receptor 1 (FFA1R) was detected by reverse transcription polymerase chain reaction (RT-PCR). ResultsIn 1 hour intervention test,FFA group versus control showed the increases of insulin secretion ［mU/(L?mg pro)］ at 5.6mmol/L glucose \[(23.8±1.6) vs (20.0±2.0)\],at 11.2mmol/L glucose \[(28.7±1.4) vs (24.5±1.5)\], and at 25mmol/L glucose \[(51.0±3.0) vs (42.6±3.4)\] (all P<0.05). In 72 hours intervention test,the similar responses occurred as in 1 hour intervention. FFA plus pioglitazone versus FFA group in both 1 and 72h showed no effect on insulin secretion (IS) at 5.6 and 11.2mmol/L glucose and showed an inhibitive effect on IS at 25mmol/L glucose.The mRNA expressions of FFA1R were not varied in each intervention group in 1 h test; and in 72 h the mRNA content of FFA1R was decreased in FFAs group（P<0.05）,IS and FFA1R expression in Pio + FFAs group was between the levels in FFAs group and control group. Conclusions Pioglitazone appears to have bidirectional regulative effect on the free fatty acids- induced impairment of insulin secretion during different action times.