Guava (Psidium guajava) belongs to the Myrtle family. It is a tropical and subtropical fruit native to the Americas. Ripe guava fruit is sweet and delicious. It is rich in vitamins A, C and trace elements such as phosphorus, calcium and magnesium. In traditional medicine, guava fruit can be eaten raw, and the roots can treat stomach problems, abdominal pain, dysentery, and diabetes; the leaves can treat diabetes, abdominal pain, rheumatism, antipyretic, stomachache, anthelmintic, cholera, vomiting, diarrhea, enteritis and other symptoms. Guava leaf extract contains polyphenols. Studies have shown that guava leaf has antioxidant, blood sugar regulating and anti-cancer effects. Not only guava leaves, research has found that guava fruits are rich in vitamins, fiber and antioxidants, which have anti-inflammatory and anti-cancer effects. Preliminary research has found that the extract of red guava young fruit has more active ingredients - saponins and total polyphenol content, and its antioxidant capacity is also higher than that of mature guava. In vitro studies have found that guava fruit extract can increase the expression of GLUT4 gene and promote the entry of blood sugar into cells. At the same time, guava fruit extract can inhibit the formation of final glycated proteins (AGEs). The purpose of this study is to explore the effect of guava fruit extract on blood sugar regulation in humans and to evaluate its potential to be developed as a blood sugar regulation supplement.