Probiotics for the management of type 2 diabetes mellitus: A systematic review and meta-analysis

Aims: To systematically review evidence of probiotic interventions against type 2 diabetes mellitus (T2DM) and analyse the effects of probiotics on glycaemic control among T2DM patients. Methods: Electronic search using five electronic databases was performed until October 2015. Relevant studies were identified, extracted and assessed for risk of bias. The primary outcomes of this review were glycated haemoglobin (HbA1c) and fasting blood glucose (FBG). Fasting plasma insulin, homeostasis model assessment-insulin resistance, C-reactive protein, interleukin-6 and malondialdehyde, were identified as the secondary outcomes. Mean differences (MD) between probiotics and control groups for all outcomes were pooled using either Fixed- or Random-Effect Model. Statistical heterogeneity was assessed using I-2 and Chi(2) tests. Results: Six randomised controlled trials (RCTs) were included in the systematic review, whereas only five were included in meta-analysis. Most RCTs were presented with low or unclear risk of bias. When compared to placebo, FBG was significantly lower with probiotic consumption (MD = -0.98 mmol/L; 95% CI: -1.17, 0.78, p < 0.00001), with moderate but insignificant heterogeneity noted. Insignificant changes between the groups were also noted for HbA1c and other secondary outcomes. Conclusions: A moderate hypoglycaemic effect of probiotics, with a significantly lower FBG was noted. Findings on HbA1c, anti-inflammatory and anti-oxidative effects of probiotics in the clinical setting, however, remain inconsistent. The findings imply the need for well-designed clinical studies to further assess the potential beneficial effects of probiotics in management of T2DM. (C) 2016 Elsevier Ireland Ltd. All rights reserved.