The present invention relates to a product of coromandel (Asystasia gangetica) and its use as a food by-product and medical value. By extracting the leaves of the coromandel (an antidiabetic agent or lactic acid bacteria promoter) for use in foods and animal feeds and dried goods, the manufacturing of a food and drinks supplement can produce an anti-diabetic effect, growth promoting effect to lactic acid bacteria and food flavor-enhancing effect. Five examples of extraction, production and recommended methods are presented.