Hypoglycemic Effect of Resveratrol: A Systematic Review and Meta-Analysis

Resveratrol (RV) is a polyphenolic compound with antioxidant, anti-inflammatory, and hypoglycemic properties. Several in vitro and animal model studies have demonstrated the beneficial effects of RV; however, the results in humans are not conclusive. After a search of different databases, 32 studies were selected for this systematic review and 30 were included in the meta-analysis. Studies that evaluated the effect of RV on glucose, insulin, HbA1c, and insulin resistance (HOMA-IR) levels were included. A significant decrease of glucose (-5.24 mg/dL, p = 0.002) and insulin levels (-1.23 mIU/L, p = 0.0003) was observed. HbA1c and HOMA-IR did not show significant changes. Due to heterogeneity, sub-analyzes were performed. Sub-analysis by dose revealed that glucose levels improve significantly after the administration of 500-1000 mg/day of RV (-7.54 mg/dL, p = 0.002), while insulin improves with doses lower than 500 mg/day (-1.43 mIU/L, p = 0.01) and greater than 1000 mg/day (-2.12 mIU/L, p = 0.03). HbA1c and HOMA-IR remained unchanged after sub-analysis by dose. Our findings suggest that RV improves glucose and insulin levels in subjects with type 2 diabetes mellitus (T2DM) and aged 45-59 years, regardless of the duration of the intervention. HbA1c improves with interventions >= 3 months. HOMA-IR does not exhibit significant changes after RV administration.