Objective To observe the differences and glucose level in plasma and serum under the current experimental condition, and the influence of the time of blood sample on detecting results.Methods The glucose level measuring was used by glucose oxidase method. Thirty blood samples from healthy physical examination were collected and with anticogulated EDTA or heprin.Results The glucose level was 0.1-0.3mmol/L higher in immediate centrifugal serum than that in plasma.Bathing the samples in 37℃ for 1h, the glucose level in serum decreased 0.9-1.1 mmol/L, and decreased 0.5 -0.7 mmol/L in plasma. Bathing the samples in 37℃ 2h later, it decreased 1.3-1.5 mmol/L in serum, and decreased 0.7-0.9 mmol/L in plasma. Placing samples in room temperature for 1h, the glucose level decreased 0.3-0.6 mmol/L in serum, and 0.2-0.3 mmol/L in plasma.For 1h in room temperature and then in 37℃ for 1h, the glucose level decreased 0.6-1.2 mmol/L in serum, and 0.3-0.7 mmol/L in plasma. Placing samples in room temperature for 2h and then in 37℃ 1h, the glucose level decreased 1.4-1.8 mmol/L in serum, and 0.7-1.1 mmol/L in plasma. Placing samples in room temperature for 3h, the glucose level decreased 0.9-1.3 mmol/L in serum, and decreased 0.8-1.0 mmol/L in plasma.Placing the centrifugal samples in 37℃ 1h, the glucose level decreased 0.5-0.6 mmol/L in serum. If placing the centrifugal samples mixed with heparin in room temperature for 1h, it only decreased 0.08mmol/L in plasma. The glucose level in immediate centrifugal samples treated with separation gel increased 0.2mmol/L than that in samples which placed in room temperature for 15min. So the changes of glucose level in blood samples revealed absolute value decreased in the course of placement.Conclusion Both the immediate centrifugal heprin-anticogulated plasma and separation gel treated serum can truly indicate the blood glucose level individually.