To confirm folk knowledge, relevant pharmacological activities previously reported were compared.
It was found that 26 species have already investigated in pharmacological activities (Table 1).
According to relevant reports, there were 2 biological activities concerning reducing blood sugar: antidiabetic activity (anti-hyperglycemic or hypoglycemic effect) and antioxidant activity.
Considering in antidiabetic mechanism, essential substances in medicinal plants may act in various roles: stimulating insulin secretion, increasing glucose uptake in muscle cells, α-glucosidase inhibitory, act like insulin, increasing glucose tolerance, decreasing insulin resistance.
For instance, Mitragyna speciosa was locally used for lowering blood sugar and it also was proven for antidiabetic activity by stimulating glucose uptake in muscle cells (Purintrapiban et al., 2011).