Overall and Sex-Specific Effect of Berberine on Glycemic and Insulin-Related Traits: a Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Berberine is widely available as a nutraceutical supplement for improving glucose metabolism. Berberine affects sex hor-mones, raising the possibility that its effects on glycemic traits and insulin sensitivity have sex disparity which has been overlooked.Objective: To assess the overall and sex-specific effects of berberine on glycemic-and insulin-related traits.Methods: We identified randomized trials of berberine versus placebo from Medline, Embase, CNKI, clinical trial registries and previous systematic reviews. Mean differences were estimated using inverse-variance weighting with random effects models. Subgroup analyses were conducted by sex, diabetes diagnosis, trial duration, berberine dose and ethnicity.Results: We identified 20 eligible studies (n = 1761). Berberine lowered fasting glucose (-0.52 mmol/L, 95% CI -0.72 to -0.33; 18 studies, n = 1522), HbA1c (-4.48 mmol/mol, 95% CI -6.53 to -2.44, 7 studies, n = 756), fasting insulin (-2.36 mU/L, 95% CI -3.64 to -1.08, 11 studies, n = 966), HOMA-IR (-0.85, 95% CI -1.16 to -0.53,12 studies, n =1065), and 2-h postprandial glucose (-1.81 mmol/L, 95% CI -2.37 to -1.24, 4 studies, n = 501). Effects on fasting glucose and HOMA-IR showed potential differences by sex, with larger reductions in women than in men. Comparing 4 studies conducted in women to one study conducted in men, the mean difference was -0.21 mmol/L (95% CI -0.41 to -0.00) for fasting glucose and -0.97 (95% CI -1.84 to -0.10) for HOMA-IR. We also found larger reductions in fasting glucose in participants with diabetes and in Asians.Conclusion: Berberine is effective in improving glucose metabolism and may result in larger effects on fasting glucose in women, in people with diabetes and in Asians, but subgroup comparisons remain to be replicated given the limited number of studies. Berberine can be considered as a complementary intervention in individuals who may benefit from modest improvements in glucose metabolism and who prefer taking a nutraceutical.Study registration: PROSPERO (CRD42022345172).