Saffron supplementation effects on glycemic indices: a systematic review and meta-analysis of randomized controlled clinical trials

Abstract

Existing evidence on the possible effects of saffron on glycemic indices were inconclusive. The aim of the present systematic review and meta-analysis was to clarify the effects of saffron supplementation on glycemic indices, including fasting blood glucose (FBG), fasting insulin, glycated hemoglobin (HbA1c), Quantitative Insulin Sensitivity Check Index (QUICKI) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) among both diabetic and non-diabetic patients. A systematic literature search of online databases PubMed, Scopus, ISI Web of science and Cochrane’s library was conducted up to August 2020. Randomized controlled trials (RCTs) investigating the effects of saffron supplementation on glycemic indices in adults were included. A total of 15 trials involving 1139 participants were included in this systematic review and meta-analysis. Saffron supplementation resulted in a significant decrease in FBS (WMD = −5.26 mg/dL; 95% CI: −10.08 to −0.44; I 2 = 89.7%), HbA1c (WMD = −0.15%; 95% CI, −0.28 to −0.02; I 2 = 79.4%,), fasting insulin (WMD = 0.12 mIU/L; 95% CI, 0.03 to 0.20; I 2 = 26.6%), and an increase in QUICKI (WMD = 0.01; 95% CI, 0.001 to 0.009; I 2 = 78.4%) compared to control. Saffron supplementation could not reduce HOMA-IR significantly (SMD = −0.21; 95% CI, −0.45 to 0.02; I 2 = 0.0%). Saffron supplements may be beneficial to improve glyceamic indices. Therefore, saffron could be considered as a valuable adjuvant therapy regarding glycemic control of patients.