TangBi Formula for Painful Diabetic Distal Symmetric Polyneuropathy: A Multicenter, Randomized, Double-Blind, Placebo-Controlled and Parallel-Group Trial

Objective: To determine whether the use of herbal medicines combined with conventional treatment is more effective than conventional medication alone in improving clinical symptoms in patients with diabetic distal symmetric polyneuropathy (DSPN).

Methods: This multicenter, placebo-controlled, double-blind, randomized controlled clinical trial recruited patients from 6 clinical centers in mainland China. A total of 188 patients were randomly assigned in a 1:1 ratio to the treatment group (Tangbi Formula plus methylcobalamin) and the control group (placebo plus methylcobalamin). Subjects were reassessed after the 24-week intervention. The primary outcomes were differences in changes in clinical signs and symptoms and changes in the Michigan Diabetic Neuropathy Score (MDNS) between the two groups before and after treatment. Secondary outcomes were changes in nerve conduction velocity (NCV) and single clinical signs and symptoms as measured by the visual-analogue scale (VAS) and Toronto clinical scoring system (TCSS).

Results: Compared with the placebo group, after 24 weeks of treatment, the MDNS score of TangBi Formula group was significantly reduced (p < 0.001). There were no significant changes in NCV results in either group before or after treatment. Compared with baseline, the difference in the change value of VAS score between the two groups after treatment was statistically significant (p = 0.031). A statistically significant difference in the change value of TCSS after treatment compared to baseline was found between the two groups (p = 0.033 at 12 weeks and p = 0.030 at 24 weeks). No severe adverse events due to study participation or study intervention were reported.

Conclusions and relevance: This trial demonstrated that combining Tangbi Formula with basal therapy can be safer and more effective in improving the symptoms of DSPN patients.