Efficacy of a Probiotic Combination on Glycemic Index and Insulin Resistance in Adults: A Systematic Review and Meta-Analysis

Insulin resistance leads to increased glucose and insulin levels. Probiotics can reduce insulin resistance, but the presence of different probiotic strains and doses prevents the generalization to real-world scenario. The current systematic review and meta-analysis study investigated the efficacy of a triple probiotic combination (<i>Lactobacillus acidophilus</i>, <i>Lactobacillus casei</i>, and <i>Bifidobacterium bifidum</i>) on glycemic index and insulin resistance parameters in adults. Randomized controlled trials evaluating the efficacy of the probiotics combination on glycemic index and insulin resistance parameters were identified. Physiotherapy Evidence Database scale and the Cochrane Risk of Bias tool were used for risk of bias assessment and RevMan for meta-analysis. Fourteen good-quality clinical trials were included in the current study. Low-to-moderate risk of bias was observed. Data from 823 participants were included. Probiotics supplementation significantly reduced insulin resistance (MD: −1.05 HOMA-IR score, <i>p</i> &lt; 0.00001), serum glucose (MD: −3.99 mg/dl, <i>p</i> = 0.0003) and insulin levels (MD: −3.79 µIU/ml, <i>p</i> &lt; 0.00001), while significantly improved insulin sensitivity (MD: +0.02 QUICKI score, <i>p</i> &lt; 0.00001) and pancreatic β-cell functioning (MD: −14.71 HOMA-B score, <i>p</i> &lt; 0.00001) compared to the control group. Significant heterogeneity was observed for all evaluation parameters (except the HOMA-B score) while no significant publication bias was observed. The current study suggests that the probiotic combination of <i>Lactobacillus acidophilus</i>, <i>Lactobacillus casei</i>, and <i>Bifidobacterium bifidum</i> is effective in reducing insulin resistance, improving glycemic index parameters, and improving pancreatic β-cell functioning in adults by improving the gastrointestinal microbiome.