Present invention features a novel use of Lactobacillus for treating type 2 diabetes, wherein the Lactobacillus is Lactobacillus reuteri GMNL-89 with the deposition numbers of BCRC 910340 and CCTCC M 207154 and comprises of live, dead bacteria or supernatant of the bacterial culture(s) and a pharmaceutically acceptable vehicle. The invention also discloses the efficacies of the indicated Lactobacillus strain including anti-oxidative enzyme activity, anti-inflammation, reduction of blood glucose level, reduction of triglycerides, reduction of total cholesterol, reduction of LDL, increase of HDL and improve insulin utilization.