In Vietnam, many herbal plants with various medicinal activities can support different diseases such as anti-anemic and antimicrobial etc including diabetic treatments. Diabetes mellitus is a group of metabolic disorders that is characterized by elevated levels of glucose in the blood. When combining the herbs following a formula, the healing effect will be more effective due to synergetic actions. Our present study assesses acute toxicity and antidiabetic activity of a new polyherbal preparation, CHM-Tieu duong, in the form of capsules. It was developed based on the traditional use of six indigenous plants from the South-Western region of Vietnam, effective in fighting diabetes, namely Andrographis paniculata (leaves), Centella asiatica (leaves), Dioscorea opposite (tuberous rhizomes), Gymnema sylvestre (leaves), Gynostemma pentaphyllum (herbs), and Morus alba (leaves). Methods: The acute toxicity was evaluated following the Organization for Economic Cooperation and Development (OECD) guidelines No. 420 using five lots of female BALB/c albino mice. The antidiabetic activity was studied using an alloxan-induced diabetic mice model on thirty BALB/c albino mice of either sex. The mice were divided into five groups, namely normal mice control group with normal saline, diabetic mice fasted control group with normal saline, diabetic mice positive control group treated with the standard drug, metformin at a dose of 100 mg/kgP, and two diabetic mice groups treated with different doses of herbal combination at 500 and 1000 mg/kgP. Resutls: The acute toxicity analysis showed that CHM-Tieu duong was orally non-toxic at a single dose of 5000 mg/kgP as it did not cause any pre-clinical changes in experimental mice. The results of the antidiabetic study showed that CHM-Tieu duong exhibited the lowering glucose levels in the alloxan-induced diabetic mice model at the high dose of 1000 mg/kgP dose. Conclusion: The findings demonstrated that CHM-Tieu duong could serve as safe and effective antidiabetic polyherbal combination.