Effects of probiotic/prebiotic/synbiotic supplementation on blood glucose profiles: a systematic review and meta-analysis of randomized controlled trials

Previous studies have evaluated the effects of probiotic/prebiotic/synbiotic supplementation on blood glucose profiles among diabetic patients. However, the results were inconsistent.Systematic review and meta-analysis.A systematic searching from PubMed, ISI Web of Science, Embase, and Cochrane Central was conducted to identify high-quality clinical trials investigating the effect of probiotic/prebiotic/synbiotic supplementation on blood glucose profiles [including fasting blood glucose (FBG), hemoglobin A1c (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR)] up to December 2020. Subgroup analyses by types or durations of probiotic/prebiotic/synbiotic supplementation were conducted to investigate the different effects among different populations.A total of 39 trials with 3517 participants were included in the final analyses. Among patients with type II diabetes (T2DM), the summarized standardized mean differences (SMDs) and 95% confidential intervals (95% CIs) of FBG, HbA1c, and HOMA-IR were -0.30 (95% CI: -0.65 to 0.05), -0.59 (95% CI: -0.88 to -0.30), and -0.68 (95% CI: -1.13 to -0.23), respectively. Among patients with gestational diabetes (GDM), the summary SMDs of FBG, HbA1c and HOMA-IR were -0.67 (95% CI: -1.23 to -0.11), -0.24 (95% CI: -0.57 to 0.08), and -1.06 (95% CI: -1.72 to -0.40), respectively. Similar improvements in blood glucose profiles were also found among persons with prediabetes or gestational woman with normal glucose, but not among patients with type I diabetes. Subgroup analyses showed similar results of probiotic supplementation for patients with T2DM and probiotic/synbiotic supplementation for patients with GDM.Probiotic/prebiotic/synbiotic supplementation might improve the blood glucose profiles among patients with T2DM/GDM, persons with prediabetes, or gestational woman with normal glucose. Trials with more sophisticated design are needed to validate the results in the future.PROSPERO CRD42020161975.