Effect of RG (Coptis root and ginseng) formula in patients with type 2 diabetes mellitus: a study protocol for a randomized controlled and double-blinding trial

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a common metabolic disease with significant health, social, and economic consequences. Traditional Chinese medicine (TCM) could effectively regulate blood sugar and influence gut microbiota in T2DM patients. Preliminary studies showed that the Coptis root and ginseng (RG) formula could relieve insulin resistance and prevent the progression of diabetes in mice. OBJECTIVES: The purpose of this study is to explore the efficacy and safety of RG formula in the treatment of adult patients with T2DM, as well as observing its effects on gut microbiota. METHODS AND ANALYSIS: This trial is a randomized, double-blind, placebo-controlled study. A total of 60 participants will be randomized in a 1:1 ratio into an experiment group (RG formula) and a control group (placebo). Patients in both groups will be given diabetes education and basic blood glucose control. Glucose-lowering drugs with significant influence on gut microbiota will be avoided. This trial will last 25 weeks including 1-week run-in, 12-week intervention, and 12-week follow-up visit. The primary outcome is the change in the HbA1c. The secondary outcomes comprise the change in the fasting blood glucose (FBG), postprandial blood glucose (PBG), fasting insulin (FIL), fasting C-peptide(C-P), insulin resistance index (IRI), inflammatory factors, and species abundance of gut microbiota between the two groups. Safety of medication will also be evaluated. The correlation analysis will be explored between the glycemic indicators, inflammatory factors, and abundance of gut microbiota. DISCUSSION: This study will provide the clinical evidence for the efficacy of RG formula in regulating blood sugar and influencing gut microbiota, which will be beneficial to form the integrated therapeutic regimen in T2DM with TCM. TRIAL REGISTRATION: “Clinical Study on the Intervention of Coptis Root and Ginseng,” Chinese Clinical Trials Registry ChiCTR 2100042126. Registered on 14 January 2021 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06229-5.