Effects of propolis supplementation on blood glucose and lipid profiles in individuals with metabolic syndrome and type 2 diabetes: a systematic review and meta-analysis

OBJECTIVE: Propolis has been suggested as a complementary therapy for improving glycemic control and lipid metabolism. However, evidence from clinical trials remains inconsistent. This systematic review and meta-analysis aimed to provide a clear and updated assessment of the effects of propolis supplementation on fasting blood sugar (FBS) and lipid profiles in individuals with type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). METHODS: A comprehensive search was conducted on the PubMed, Scopus, Cochrane Library, and Web of Science databases through December 2024 to identify randomized controlled trials (RCTs) evaluating the impact of propolis supplementation on FBS and lipid parameters. Eligible data were pooled using a random-effects model, and weighted mean differences (WMDs) were calculated as pooled effect sizes. RESULTS: A total of 12 RCTs were included, encompassing 736 participants. Propolis supplementation significantly reduced FBS (WMD, -12.08 mg/dL; 95% confidence interval [CI], -19.13 to -5.04; P=0.001) and triglyceride (TG) levels (WMD, -25.40 mg/dL; 95% CI, -44.21 to -6.59; P=0.008) without significantly affecting the levels of total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. CONCLUSION: These findings suggest that propolis supplementation may modestly improve glycemic control and reduce TG levels in individuals with T2DM and MetS. However, the limited number of available studies and relatively small sample sizes highlight the need for large, high-quality RCTs to verify these findings and clarify the metabolic effects of propolis.