Effect of probiotics on metabolic profiles in type 2 diabetes mellitus: A meta-analysis of randomized, controlled trials

Abstract

Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disease which is imposing heavy burden on global health and economy. Recent studies indicate gut microbiota play important role on the pathogenesis and metabolic disturbance of T2DM. As an effective mean of regulating gut microbiota, probiotics are live micro-organisms that are believed to provide a specific health benefit on the host. Whether probiotic supplementation could improve metabolic profiles by modifying gut microbiota in T2DM or not is still in controversy.The aim of the study is to assess the effect of probiotic supplementation on metabolic profiles in T2DM.We searched PubMed, EMBASE, and Cochrane Library up to 12 April 2016. Two review authors independently assessed study eligibility, extracted data, and evaluated risk of bias of included studies. Data were pooled by using the random-effect model and expressed as standardized mean difference (SMD) with 95% confidence interval (CI). Heterogeneity was assessed and quantified (I).A total of 12 randomized controlled trials (RCTs) were included. Lipid profiles (n = 508) and fasting blood glucose (FBG) (n = 520) were reported in 9 trials; the homeostasis model of assessment for insulin resistance index (HOMA-IR) (n = 368) and glycosylated hemoglobin (HbA1c) (n = 380) were reported in 6 trials. Probiotics could alleviate FBG (SMD -0.61 mmol/L, 95% CI [-0.92, -0.30], P = 0.0001). Probiotics could increase high-density lipoprotein-cholesterol (HDL-C) (SMD 0.42 mmol/L, 95% CI [0.08, 0.76], P = 0.01). There were no significant differences in low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), triglyceride (TG), HbA1c and HOMA-IR between the treatment group and the control group.Probiotics may improve glycemic control and lipid metabolism in T2DM. Application of probiotic agents might become a new method for glucose management in T2DM.

Figure 1

Flowchart of the study selection.

Figure 2

The methodological quality of included studies.

Figure 3

Forest plot of randomized controlled trials comparing the effect of probiotics on FBG with placebo in T₂DM. Weighted mean differences (95% CIs) for FBG are shown. Pooled estimates calculated by the random-effect method. The squares indicate the effect of probiotics in a particular study. The horizontal lines represent 95% confidence intervals (CIs). The diamond indicates the pooled effect. CI = confidence interval, FBG = fasting blood glucose, IV = inverse variance, T₂DM = type 2 diabetes mellitus.

Figure 4

Forest plot of randomized controlled trials comparing the effect of probiotics on lipid profiles with placebo in T₂DM. Weighted mean differences (95% CIs) for (A) HDL-C, (B) LDL-C, (C) TC, (D) TG are shown. Pooled estimates calculated by the random-effect method. The squares indicate the effect of probiotics in a particular study. The horizontal lines represent 95% confidence intervals (CIs). The diamond indicates the pooled effect. CI = confidence interval, HDL-C = high-density lipoprotein-cholesterol, LDL-C = low-density lipoprotein-cholesterol, IV = inverse variance, TG = triglyceride, TC = total cholesterol, T₂DM = type 2 diabetes mellitus.

Figure 5

Forest plot of randomized controlled trials comparing the effect of probiotics on HbA1c with placebo in T₂DM. Weighted mean differences (95% CIs) for HbA1c are shown. Pooled estimates calculated by the random-effect method. The squares indicate the effect of probiotics in a particular study. The horizontal lines represent 95% confidence intervals (CIs). The diamond indicates the pooled effect. CI = confidence interval, HbA1c = glycosylated hemoglobin, T₂DM = type 2 diabetes mellitus.

Figure 6

Forest plot of randomized controlled trials comparing the effect of probiotics on HOMA-IR with placebo in T₂DM. Weighted mean differences (95% CIs) for HOMA-IR are shown. Pooled estimates calculated by the random-effect method. The squares indicate the effect of probiotics in a particular study. The horizontal lines represent 95% confidence intervals (CIs). The diamond indicates the pooled effect. CI = confidence interval, HOMA-IR = homeostasis model of assessment for insulin resistance index, T₂DM = type 2 diabetes mellitus.

Figure 7

Publication bias. (A) Funnel plots, (B) Egger's publication bias plot.