To study the efficacy and safety of the Jiang Tang Fang Long Jiao Nang (Hypoglycemic Anti-Deafness Capsule) in treating non-insulin dependent diabetes mellitus with hearing loss. Methods Two hundred ninety six patients with non-insulin dependent diabetes mellitus and hearing loss were randomly assigned to a treatment group(n=164, 208 ears) and a control group(n=132,184 ears). Patients in the treatment group were treated with the Jiang Tang Fang Long Jiao Nang and supplement herbal preparations as indicated by traditional Chinese medicine dialectical assessment, while control patients received glibenclamide and conventional treatments for deafness. Hearing, fasting blood glucose (FBG), post-prandial blood glucose(PBG), 24 hour urine sugar, platelet function indices, blood superoxide dismutase (SOD) and lipid peroxides (LPO) levels, and symptom improvement were compared between the two groups. Results The rate of hearing improvement was 56.7% for the treatment group and 26.6% for the control. FBG, PBG and 24 hour urine sugar improved in both groups, but the last two were superior in the treatment group compared to the control. Symptoms improvement was also superior in the treatment group compared to the control. In patients receiving Jiang Tang Fang Long Jiao Nang treatment, platelet function indices, SOD and LPO were all improved, while only LOP improvement was noticed in control patients. No acute or long-term toxicity was demonstrated for the Jiang Tang Fang Long Jiao Nang in animal tests. The Jiang Tang Fang Long Jiao Nang lowered blood glucose and serum triglycerides in a rat model of alloxan-induced diabetes. Conclusion The Jiang Tang Fang Long Jiao Nang is effective in improving hearing and diabetic indices in diabetic patients with deafness, without significant side effects.