The Effect of Microbiome-modulating Probiotics, Prebiotics and Synbiotics on Glucose Homeostasis in Type 2 Diabetes: A Systematic Review, Meta-Analysis, and Meta-Regression of Clinical Trials.

This was a systematic review, meta-analysis, and meta-regression of clinical trials in adults with type 2 diabetes from diverse geographic regions. One included Iran trial randomized 20 participants to the probiotic arm and 20 to control; the active arm had a mean age of 45.00 ± 5.37 years, 7 men and 13 women, and BMI 31.94 ± 5.76.

The review evaluated microbiome-modulating nutraceuticals as adjuncts to usual diabetes care, including probiotics, prebiotics, and synbiotics. In the extracted active arm, adults with type 2 diabetes received one oral capsule daily for 8 weeks containing Lactobacillus casei 10^8 CFU with maltodextrins, versus control.

Overall, pro/pre/synbiotic supplementation improved glucose homeostasis in adults with type 2 diabetes. The meta-analysis found significant reductions in fasting plasma glucose, HbA1c, fasting insulin, and HOMA-IR, along with improved QUICKI, while C-peptide did not change significantly. Effects varied by age, baseline BMI, baseline biomarker values, dose, duration, nutraceutical type, and recruitment region. Synbiotics, particularly multispecies formulations, showed notable HbA1c benefits and support these nutraceuticals as potential adjuncts to pharmacological therapy.

The evidence base was highly heterogeneous in formulation, dose, duration, participant characteristics, and region, which limits comparability and precision. Effects appeared to depend on baseline status and trial design, and the authors called for standardized, prespecified multicenter trials with fuller baseline and microbiome data.