Recently great attention has been forwarded to natural products especially those owing medicinal properties e.g. Korean ginseng roots, Nigella sativa, Curcuma longa and green tea. In our study we select the last product as drinking tea is a traditional dietary habit in Egypt. Green tea, catechin is its active constituent, has received a great attention as a protective agent against cancer and cardiovascular diseases. Data reported regarding the effect of catechin on carbohydrate metabolism are scarce few of them referred to its hypoglycemic effect, but without a definite explanation for the exact mechanism of action. The present work aimed mainly to study some of the metabolic actions of catechin. Metformin (Biguanide) which is a well known hypoglycemic drug has been included for comparison. Administration of both catechin and metformin individually for four and ten weeks respectively to normal and alloxan diabetic rats was done. Parameters studied were blood glucose, lactate, pyrurvate, liver glycogen, insulin, total cholesterol (TG), triacylglycerol (1G), non esterified fatty acids (NEFA) and lipid peroxidation product(MDA).