Role of probiotics/synbiotic supplementation in glycemic control: A critical umbrella review of meta-analyses of randomized controlled trials

The evidence regarding the beneficial effects of probiotics/synbiotic supplementation have been revealed by several meta-analyses, however some of these studies have fielded inconsistent results and a conclusion has yet to be reached. Therefore, the aim of present umbrella meta-analyses was to assess relevant evidence and elucidate the efficacy of probiotics/synbiotic supplementation in glycemic control. A comprehensive search in four databases (Cochrane library, PubMed, Web of science and Scopus) was performed to collect relevant studies up to August 2022, the pooled effects were measured with the use of random/fix-effect model depends on the heterogeneity. A total of 47 eligible meta-analyses involving 47,720 participants were identified to evaluate the pooled effects. The overall results showed that probiotics/synbiotic supplementation delivered significant decreases in fast plasma glucose (ES = −0.408, 95% CI: −0.518, −0.298; P < 0.001; I2 = 82.996, P < 0.001), fast plasma insulin (ES = −1.165, 95% CI: −1.454, −0.876; P < 0.001; I2 = 89.629, P < 0.001), homeostasis model assessment of insulin resistance (ES = −0.539, 95% CI: −0.624, −0.454; P < 0.001; I2 = 56.716, P < 0.001), and glycosylated hemoglobin (ES = −0.186, 95% CI: −0.270, −0.102; P < 0.001; I2 = 59.647, P = 0.001). Subgroup analysis showed that patients with impaired glucose homeostasis might benefit the most from probiotics/synbiotic supplementation. In conclusion, current umbrella meta-analysis strongly supporting the beneficial health effects of probiotics/synbiotic supplementation in glycemic control.