Lagerstroemia speciosa Pers., belongs to the Horoscope Lythraceae, is a large tree with broad foliage, 10 - 13cm high. Sometimes it has brown spines, smooth round branches; alternate, oval or broad ovoid leaves; pinkish purple flowers, ovoid capsule.

Lagerstroemia grows mainly in southern provinces, only met in the North in Muong Te (Lai Chau), Tuong Duong, Quy Chau Nghe An) and Quang Binh.

The plant contains an active substance similar to insulin, which has hypoglycemic activity with 440 units of insulin / g, which has the highest concentration in ripe leaves and fruits when fresh.

In the Philippines, Lagerstroemia extract has the effect of lowering blood sugar through oral administration. Three compounds of the ellogitanin group: lagerstroemin, florin B and reginin A, are considered active substances.

According to Alan R. Gaby (2006) The Natural pharmacy, published in New York, USA, page 162: Research results on patients with type 2 diabetes, Lagerstroemia extract, after 2 weeks of treatment with standard 32 - 4.8mg dose contains 1% corosolic acid, blood sugar content decreases by an average of 20 - 30%.

Recently, within a ministry-level project of the Hanoi University of Pharmacy, Lagerstroemia has also been shown to be the most potent hypoglycemic drug among the drugs that have been screened for research.