The Clinical Efficacy of Gegen Qinlian Decoction in Treating Type 2 Diabetes is Positively Correlated with the Dose of Coptidis rhizoma: Three Randomized, Doubleblind, Dose-Parallel Controlled Clinical Trials

Background: The results of Study 1 we have published proved that medium and high doses of Gegen Qinlian Decoction (GQD) were effective in treating type 2 diabetes (T2D) with damp-heat syndrome. However, whether the main drug of GQD in treating T2D was Puerariae Lobatae Radix or Coptidis Rhizoma has always been a hot topic of debate among many doctors. Therefore, we conducted Study 2 and Study 3 to determine the main drug of GQD for treating T2D. Methods: Both Study 2 and Study 3 were randomized, double-blind, dose-parallel controlled, multicenter trials. In Study 2, Puerariae Lobatae Radix was used as the main drug, and in Study 3, Coptidis Rhizoma was used as the main drug. About 120 patients with newly diagnosed T2D were enrolled in each study and randomized 1:1:1 to three treatment groups. The three treatment groups were named HD, MD, and LD groups according to the high, medium, and low doses of the main drug. The course of treatment was 12 weeks. The primary outcomes were the changes in HbA1c. Results: In Study 2, the HbA1c decreased by 0.58 (0.87), 0.28 (1.17), and 0.55 (0.85) in the HD, MD, and LD groups, respectively, with no significant difference between treatment groups according to covariance analysis (F=0.66, P=0.5206). In Study 3, the HbA1c decreased by 0.75 (0.82), 0.34 (0.71), and 0.26 (0.79) in the HD, MD, and LD groups respectively. By analysis of covariance, the change values of HbA1c were significantly different among the three groups (F=3.11, P=0.0492). Conclusion: The changes in HbA1c were positively correlated with the dose of Coptidis Rhizoma, but not significantly with the dose of Puerariae Lobatae Radix. It demonstrated that the main drug of GQD in treating T2D patients is Coptidis Rhizoma.