Effect of herbal tea on glycemic control in patients with type 2 diabetes: Protocol for a systematic review and meta-analysis

BACKGROUND: Type 2 diabetes (T2D) is a significant health concern worldwide, and good glycemic control is the basis of avoiding disease progression. Herbal tea, as a convenient and effective medication method, has gained popularity among many diabetic patients. However, there are no systematic reviews or meta-analyses to evaluate the clinical efficacy of herbal tea on T2D. METHODS: Four English electronic databases and 4 Chinese electronic databases were searched for randomized controlled trials (RCTs) meeting inclusion criteria; Clinical trials were searched to explore the relevant unpublished data. Fasting blood glucose and glycated hemoglobin will be measured as primary outcomes. Secondary outcomes include 2-hour postprandial blood glucose, fasting insulin, and homeostasis model assessment-insulin resistance. The heterogeneity of data will be investigated by Chi-square and I test; subgroup analysis and sensitivity analysis will be conducted to explore the sources of heterogeneity; funnel plot will be used to evaluate publication bias; finally, we will use grading of recommendations assessment, development, and evaluate system method to evaluate the quality of evidence. Merging analysis of data will be performed using Rev Man 5.3 software. RESULTS: The results will be published in a peer-reviewed journal. CONCLUSIONS: The systematic review will confirm whether herbal tea consumption is benefit to the glycemic control in patients with T2D. PROSPERO REGISTRATION NUMBER: CRD42019129863.