Zingiber officinale Roscoe (Ginger) and its Bioactive Compounds in Diabetes: A Systematic Review of Clinical Studies and Insight of Mechanism of Action

Background: Zingiber officinale Roscoe (Ginger) belongs to the Zingiberaceae family, which is renowned for its rich nutritional and phytochemical composition, and has been validated for its anti-diabetic and anti-inflammatory properties via in vitro, in vivo, and clinical studies. Nonetheless, a comprehensive review of these pharmacological studies, especially clinical studies, together with an analysis of the mechanism of action of the bioactive compounds is still lacking. This review provided a comprehensive and updated analysis of the anti-diabetic efficacy of Z. officinale and its compounds ginger enone, gingerol, paradol, shogaol, and zingerone. Methods: The present systematic review was conducted using the PRISMA guidelines. Scopus, ScienceDirect, Google Scholar, and PubMed were the main databases used for retrieving information from inception to March 2022. Results: From the findings obtained, Z. officinale can be regarded as a therapeutic species showing significant improvement in clinical studies on glycemic parameters (Fasting blood glucose (FBG), hemoglobin A1C (HbA1c), and insulin resistance). In addition, the bioactive compounds of Z. officinale act via several mechanisms as revealed by in vitro and in vivo studies. Overall, these mechanisms were by increasing glucose-stimulated insulin secretion, sensitising insulin receptors and raising glucose uptake, translocation of GLUT4, inhibition of advanced glycation end product-induced increase of reactive oxygen species, regulation of hepatic gene expression of enzymes associated with glucose metabolism, regulation of the level of pro-inflammatory cytokines, amelioration of the pathological injuries of kidneys, protective effect on the morphology of β-cells as well as its antioxidant mechanisms, among others. Conclusion: Z. officinale and its bioactive compounds displayed promising results in in vitro and in vivo systems, nevertheless, it is highly recommended that human trials be conducted on these compounds since clinical studies are the core of medical research and considered the final stages of the drug development process.