The relation between the activity of the sperm specific glyceraldehyde-3-phosphate dehydrogenase (GAPDS) and the motility of sperms in diabetic men was investigated. It was found that the mean value of GAPDS activity and sperm motility in diabetic sperm samples is lower than that in normal samples. The activity of GAPDS protein was significantly positive correlation with sperm motility (R = 0.96) and significantly negative correlation with the incidence of infertility (R = -0.99). The fluorescence intensity of GAPDS protein in sperms of 2-diabetic patients (>5years, n = 88) was significantly lower than that in normal control group. The location rate of GAPDS protein in sperms of diabetic men was also significantly lower compared with that found in samples from non-diabetic men. Exogenous GAPDS protein can diminish ROS content in sperms and promote sperm motility at the concentration of over 5 ug/ml GAPDS. Based on the literature data on the importance of GAPDS for the motility of sperms in diabetic men, it was concluded that the decrease in the sperm motility and GAPDS activity in the presence of high glucose or diabetes mellitus is due to oxidation of GAPDS and inhibition of glycolysis by the reactive oxygen species produced by sperms.