Effect of saffron and fenugreek on lowering blood glucose: A systematic review with meta-analysis

Saffron and fenugreek have been shown to have an effect on lowering blood glucose; therefore, this study aims to evaluate the effects of using saffron and fenugreek on blood glucose control. PubMed, Cochrane Library, Scopus, and Web of Science databases were searched for relevant articles. Articles on the use of saffron or fenugreek to control blood glucose were selected in compliance with PRISMA guidelines. R software was used for statistical analysis. The mean difference (MD) and the standardized MD (SMD) were adopted, and subgroup analyses were performed according to patient's clinical condition. Nineteen studies comprised this meta-analysis. Overall, using fenugreek decreased fasting blood glucose (FBG) (SMD: -0.90; 95%CI: -1.43 to -0.38; I²  = 87%; p < 0.001), postprandial blood glucose (PPBG) (SMD: -1.13; 95%CI: -1.99 to -0.28; I²  = 94%; p < 0.001), and glycated hemoglobin (HbA1c) (SMD: -0.43; 95%CI: -0.75 to -0.12; I²  = 20%; p = 0.29). Saffron supplementation reduced FBG (MD: -9.06 mg/dl; 95%CI: -16.25 to -1.86; I²  = 40%; p = 0.12) and HbA1c (MD: -0.19%; 95%CI: -0.23 to -0.14; I²  = 0%; p > 0.99). Our results show that using saffron and fenugreek can reduce FBG, PPBG, and HbA1c; however, there are some shortcomings that require attention for these results. Further high-quality studies should be conducted to establish the clinical efficacy of herbal medicines.