Male Wistar rats were divided into two groups by random. One group was injected with streptozotocin(STZ) 30 mg/kg BW via tail vein. Three weeks later, the rats were fed on diet of high fat, high sucrose and high calorie for another 8 weeks. There were 38 rats with impaired glucose tolerance and insulin level higher or equal to the control group selected as the diabetic model group. Another 36 rats not injected with STZ and fed on normal diet were selected as controls. The two groups were divided into two subgroups and fed with normal diet for another 4 weeks. The four subgroups were normal control group, normal +SH group, diabetes control group and diabetes +SH group. The rats in normal +SH group and diabetes +SH group were tube feeding every day with silk hydrate (SH) 1.0 g/kg BW for 4 weeks. The results showed that in the diabetes +SH group, the glucose tolerance, blood lipid and the predictive index of coronary heart disease were significantly improved, but no effect on their blood insulin level. There was no change in the normal +SH group. The results suggested that SH could modulate the metabolism of blood glucose and partly improve the disorder of the serum lipid of diabetic rats.