A medicinal preparation, a process, a nutritional composition and regenerative and insulin potentiating method for humans and also for mammals for prevention, treatment and management{HEAD ~ /glycemic control} of {TAIL ~ diabetes mellitus} by obtaining optimum glucose level in blood, by administering an extract of Costus pictus to produce above effect in a dose of 500 2000mg/day in humans and 50 200mg/kg/day in rats 