Ethnopharmacological relevance: Momordica charantia Linnaeus (Cucurbitaceae) has been extensively used traditionally as food and herbal medicine for type 2 diabetes mellitus in Asia, Brazil, and east Africa. In vitro and in vivo studies suggest its glycemic control potential; however, clinical studies produced conflicting results.
Aim of the study: To evaluate the efficacy of M. charantia preparations in lowering elevated plasma glucose level in prediabetes and type 2 diabetes mellitus patients.
Methods: Electronic search of the Cochrane library, PubMed®, CINAHL, and SCOPUS databases was done from 1st January 1960-30th April 2018 without language restriction. Two independent reviewers extracted data and assessed risk of bias of articles. Revman var. 5.3 software was used for data synthesis in meta-analysis. Heterogeneity was assessed using Chi-square and I2 tests. Treatment effect was estimated using mean difference at follow up in outcome measures between M. charantia preparations and placebo or oral hypoglycemic agents control group. The protocol of this study has a registration number PROSPERO CRD42018083653.
Results: Ten studies of type 2 diabetes mellitus (n = 1045) were included in the meta-analysis. They had 4-16 weeks follow up and overall moderate to high risk of bias. Compared to placebo, M. charantia monoherbal formulation significantly reduces FPG, PPG and HBA1c with mean difference of - 0.72 mmol/L, (95% CI: -1.33, -0.12), I2 = 14%, - 1.43 mmol/L, (95% CI: -2.18, -0.67), I2 = 0, - 0.26%, (95% CI: -0.49, -0.03), I2 = 0 respectively. M. charantia also lowered FPG in prediabetes (mean difference -0.31 mmol/L, n = 52); the evidence was downgraded to low quality because the study had unclear risk of bias and inadequate sample size. No serious adverse effects were reported.
Conclusion: M. charantia adjunct preparations improved glycemic control in T2DM patients. However, this conclusion is based on low to very low quality evidences for the primary outcomes and sparse data for several safety outcomes, thus, warrant further research. Particularly needed are the researches that focus on standardizing M. charantia formulation and determine its efficacy and safety in clinical trials with adequate sample size, designed with random sequence generation, allocation concealment of intervention and blinding of both research personnel and participants.
Keywords: Bitter gourd; Efficacy; Meta-analysis; Prediabetes; Safety; Type 2 diabetes mellitus.
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