A Meta-analysis of the Effects of Probiotic Supplementation on Type 2 Diabetes Parameters

We aimed to assess the effect of probiotic supplementation on type 2 diabetes (T2D) related variables. Randomized controlled trials (RCTs) were systematically searched from PubMed, Springer-link and Scopus data bases published between 2016 and 2020. Collected studies were independently assessed for eligibility, data extracted and evaluated for risk of bias. Statistical analysis was performed using RevMan 5.4.1. The effects of probiotics were assessed for: body mass index (BMI), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), homeostasis, model assessment-estimated insulin resistance (HOMA-IR), insulin, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), systolic blood pressure (SBP), diastolic blood pressure (DBP) and high-sensitivity C-reactive protein (hs-CRP). From 1702 identified studies, eight trials were eligible for systematic review and six were included in the final meta-analysis. Probiotic strain levels increased without any change on microbiota diversity. Abundant phyla were Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Verrucomicrobia, and Cyanobacteria. Significant effects were found for FBG (SMD –0.53) and HOMA-IR (SMD –0.61). No significant effect were found for BMI (MD –0.55 kg/m2), HbA1c (MD –0.13%), insulin (MD –1.77 μU/mL), TG (SMD –0.17), TC (SMD –0.13), LDL-C (SMD –0.09), HDL-C (SMD 0.21), SBP (MD –3.42 mmHg), DBP (MD –2.27 mmHg) and hs-CRP (SMD –0.05). No serious adverse events were reported for eligible trials, no important heterogeneity for FBG and HOMA-IR and no significant publication bias were found. Our findings indicate that the probiotic has a significant effect on FBG and HOMA-IR. Also, they improve BMI, TG, TC, LDL-C, HDL-C, HbA1c, insulin, hs-CRP, SBP and DBP.