Abstract： Objective To study the effects of supra-physiologic glucose on the expression of PDX-1 and insulin secretion. Methods Islet cells isolated from SD rats were incubated in medium containing 5.6 mmol/L or 33 mmol/L glucose respectively for 3 days. Basic and glucose-induced insulin levels in supernate and in islet cells were detected. The PDX-1 mRNA and protein were detected. Results (1) Islet cells exposed to 33 mmol/L vs 5.6 mmol/L glucose for 3 days showed significant decrease in the basic and glucose-induced insulin release, and in cell insulin content and PDX-1 protein. (2) Prolonging incubation of islet cells in 33 mmol/L glucose aggravated the inhibitive effect on PDX-1 expression and insulin secretion. (3)Recovery to normal concentration of glucose in 3 days could partly improve PDX-1 expression and insulin secretion. Conclusions Inhibition of PDX-1 is one of the mechanism of glucotoxicity, and recovery to normal concentration of glucose in 3 days can partly improve PDX-1 expression and insulin secretion.