The study examined the effects of dietary green tea powder supplementation on blood glucose, and plasma and liver lipid concentrations in diabetic rats. Twenty-five male Sprague-Dawley rats (body weight $200{pm}5;g$) were divided into two groups (diabetic and non-diabetic), which were each randomly divided into two subgroups that were fed a control and 1% green tea powder-supplemented diet. Serum and liver lipid concentrations were measured by established techniques. Low density lipoprotein-cholesterol (LDL-C) was calculated from an established equation. Body weight gain and feed efficiency ratio were lower in diabetic rats than in non-diabetic rats regardless of diet. There were no differences in weight gain in diabetic and non-diabetic rats consuming the control and green tea powder-supplemented diets. The levels of fasting plasma glucose, serum total cholesterol, triglyceride, LDL-C and atherogenic index of diabetic rats were significantly higher than that of non-diabetic rats. Conversely, the levels of high density lipoprotein-cholesterol (HDL-C) of diabetic rats was significantly lower than that of non-diabetic rats. Fasting plasma glucose, serum total cholesterol, triglyceride, LDL-C and atherogenic index were significantly lower in diabetic rats fed the green tea powder diet than in rats fed the control diet, and HDL-C was significantly higher in rats fed the green tea powder diet than in rats fed the control diet. The content of liver total cholesterol and triglyceride of diabetic rats were significantly higher than that of non-diabetic rats. Liver total cholesterol and triglyceride were significantly lower in diabetic rats fed green tea powder-supplemented diet than in rats fed the control diet. It is concluded that green tea powder supplementation positively influences blood glucose and lipid metabolism in diabetic rats. The present study, although not directly applicable to humans, may have some implications for individuals who habitually consume green tea powder.