Relative quantitation RT-PCR was used to investigate the regulation of leptin expression in 3T3-F442A adipocytes by glucose and insulin. The results showed that glucose and insulin stimulated the expression of leptin in 3T3-F442A adipocytes, but they did not act synergically. Over-high concentration of glucose suppressed the expression of leptin and the effect of insulin. The elevation of the expression of leptin was characterized with saturation. The concentration of glucose is very important for the regulation of leptin expression.