The efficacy and safety of Momordica charantia L. in animal models of type 2 diabetes mellitus; A systematic review and meta-analysis

BackgroundMomordica charantia L. (Cucurbitaceae) has been used to control hyperglycemia in people with type 2 diabetes mellitus in Asia, South America, and Africa for decades. However, a meta-analysis of clinical trials confirmed very low-quality evidence of its efficacy. To potentially increase the certainty of evidence, we evaluated the effect of M. charantia L. in comparison with vehicle on glycemic control in animal models of type 2 diabetes mellitus.\n\nMethodsReview authors searched in MEDLINE, Web of Science, Scopus, and CINAHL databases without language restriction through April 2019. Two authors independently evaluated full texts, assessed the risk of bias, and extracted data. We analyzed the influence of study design and evidence of publication bias.\n\nResultsThe review included 66 studies involving 1861 animals. They had a follow up between 7 and 90 days. Majority 29 (43.9%) used Wistar albino rats, and 37 (56.1%) used male animals. Thirty-two (48%) used an aqueous extract of fresh fruits. M. charantia L. reduced fasting plasma glucose (FPG) and glycosylated hemoglobin A1c in comparison to vehicle control (42 studies, 815 animals; SMD, -6.86 [95% CI; -7.95, -5.77], 3 studies, 59 animals; SMD; -7.76 [95%CI; -12.50, -3.01]) respectively. Magnitude of FPG was large in Wistar albino rat subgroup; SMD; -10.29, [95%CI; -12.55, -8.03]. Publication bias changed FPG to non-significant -2.46 SMD, [95%CI; - 5.10, 0.17]. We downgraded the evidence to moderate quality due to poor methodological quality, high risk of bias, unexplained heterogeneity, suspected publication bias, and lack of standardized dose.\n\nConclusionM. charantia L. lowers elevated plasma glucose level in type 2 diabetes mellitus animal models. Publication bias and poor methodological quality call for future researches to focus on standardizing dose with chemical markers and provide measures to improve preclinical type 2 diabetes mellitus studies.\n\nSystematic review registration CRD42019119181