Lycium barbarum polysaccharide (LBP) has traditionally been used in Chinese medicine as a chief ingredient of Lycium barbarum (wolf berry/goji berry) for the treatment of various diseases with the symptoms of frequent drinking and urination. This study was conducted as a randomized, controlled clinical trial. A total of 67 patients with type 2 diabetes (30 in control group and 37 in LBP group) were enrolled in this prospective, randomized, double-blind study (administration at 300 mg/day body weight). In order to observe the hypoglycemic and lipid-lowering activity of LBP in patients with type 2 diabetes after dinner, various tests were conducted between control and LBP intervention groups in 3 months. Although, the study had small sample size and short follow-up, significant findings were observed. The results of our study indicated a remarkable protective effect of LBP in patients with type 2 diabetes. Serum glucose was found to be significantly decreased and insulinogenic index increased during OMTT after 3 months administration of LBP. LBP also increased HDL levels in patients with type 2 diabetes. It showed more obvious hypoglycemic efficacy for those people who did not take any hypoglycemic medicine compared to patients taking hypoglycemic medicines. This study showed LBP to be a good potential treatment aided-agent for type 2 diabetes.