Abstract: Objective To study the effects of Meilian Xiaoke capsule (a traditional Chinese medicinal preparation) combined with
metformin for protecting islet cells and lowering blood glucose in diabetic rats. Methods Rat models with type 2 diabetes,
established by high-fat and high-glucose diet combined with streptozotocin (STZ) injection, were treated with a low dose of
metformin, Meilian Xiaoke capsule, or both for 4 weeks by gavage. Blood glucose level was tested in the rats, and islet
pathologies and changes in islet β cell number after the treatment were observed with HE staining and aldehyde fuchsin
staining, respectively. Results Treatment with metformin or Meilian Xiaoke capsule alone for 2 or 4 weeks did not produce
significant improvement of blood glucose in the diabetic rats. Their combined treatment for 4 weeks resulted in significantly
lowered blood glucose level and improved glucose tolerance with also obviously increased islet β cell number and lessened
islet pathologies. Conclusion Meilian Xiaoke capsule and metformin show a synergistic effect to significantly enhance the
therapeutic effect in rats with type 2 diabetes.