Effectiveness of Medicinal Plants for Glycaemic Control in Type 2 Diabetes: An Overview of Meta-Analyses of Clinical Trials
Merlin Willcox, Christina Elugbaju, Marwah Al-Anbaki, Mark Lown, Bertrand Graz
Abstract
Aims: To rank the effectiveness of medicinal plants for glycaemic control in Type 2 Diabetes (T2DM). Methods: MEDLINE, EMBASE, CINAHL and Cochrane Central were searched in October 2020. We included meta-analyses of randomised controlled clinical trials measuring the effectiveness of medicinal plants on HbA1c and/or Fasting Plasma Glucose (FPG) in patients with T2DM. Results: Twenty five meta-analyses reported the effects of 18 plant-based remedies. Aloe vera leaf gel, Psyllium fibre and Fenugreek seeds had the largest effects on HbA1c: mean difference –0.99% [95% CI−1.75, −0.23], −0.97% [95% CI −1.94, −0.01] and −0.85% [95% CI −1.49, −0.22] respectively. Four other remedies reduced HbA1c by at least 0.5%: Nigella sativa , Astragalus membranaceus, and the traditional Chinese formulae Jinqi Jiangtang and Gegen Qinlian. No serious adverse effects were reported. Several other herbal medicines significantly reduced FPG. Tea and tea extracts ( Camellia sinensis ) were ineffective. However, in some trials duration of follow-up was insufficient to measure the full effect on HbA1c (<8 weeks). Many herbal remedies had not been evaluated in a meta-analysis. Conclusion: Several medicinal plants appear to be as effective as conventional antidiabetic treatments for reducing HbA1c. Rigorous trials with at least 3 months’ follow-up are needed to ascertain the effects of promising plant-based preparations on diabetes.