Costus igneus, commonly known as insulin plant in India, belongs to the family Costaceae. Consumption of the leaves are believed to lower blood glucose levels, and diabetics who consumed the leaves of this plant did report a fall in their blood glucose levels.
What is the Costus igneus plant? 

Costus igneusTrusted Source, or “insulin plant,” comes from Eastern Brazil. It’s a perennial spreading plant that can reach about 2 feet tall.

Those who use this plant consume it in the following ways:

chew on the leaves

consume the benefits of the leaves as a supplement in tablet form

eat the ground powder made from the leaves

boil the leaves to make a tea

In Southern India and other parts around the world, people with diabetes use the leaves as a dietary supplement. Additionally, Costus igneus is an antioxidant that can be used to help the immune system defend against bacterial infections. It’s also a diuretic.