The Effect of Probiotics/synbiotics Supplementation on Renal and Liver Biomarkers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials

Despite the apparent beneficial effects of probiotics/synbiotics on glucose hemostasis, lipid profile, and inflammatory responses, it is not clear whether these beneficial effects also impact renal and hepatic function in diabetes. Therefore, we sought to assess the effect of probiotics/synbiotics supplementation on renal and liver biomarkers in adults with type 2 diabetes (T2DM) using a systematic review and meta-analysis of randomized controlled trials (RCTs). PubMed, Scopus, Web of Science, and Cochrane Library were systematically searched, up to February 2021. The pooled weighted mean difference (WMD) was estimated using a random-effect model. The methodological quality of studies, as well as certainty of evidence, was assessed using standard scales. Fifteen related trials were identified. Meta-analysis of six trials, involving 426 participants, indicated that probiotics/synbiotics supplementation reduced serum levels of creatinine (WMD= -0.10 mg/dl, 95% CI: -0.20, -0.00; P= 0.01; I2= 87.7%; P-heterogeneity<0.001), without any significant effect on blood urea nitrogen (BUN), glomerular filtration rate, or microalbuminuria. No significant improvement was found on liver biomarkers following probiotics/synbiotics supplementation. The subgroup analysis showed a significant improvement in BUN when follow-up duration lasted for 12 weeks or more (WMD= -1.215 mg/dl, 95% CI: -1.933, -0.496 ; P= 0.001), and in creatinine levels in patients with renal dysfunction (WMD= -0.209 mg/dl, 95% CI: -0.322, -0.096; P<0.001). Our results are insufficient to advocate the use of probiotics/synbiotics for improving renal or liver function in patients with T2DM. Indeed, due to the low certainty of evidence, these findings need to be affirmed in further high-quality RCTs.