Effects of Probiotic Supplementation on Dyslipidemia in Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials

The effectiveness of probiotic consumption in controlling dyslipidemia in type 2 diabetes mellitus (T2DM) has been unclear. We reviewed relevant randomized controlled trials (RCTs) to clarify the effect of probiotic intake on dyslipidemia in T2DM patients. The Web of Science, Scopus, PubMed and Cochrane Library databases were used for searching relevant RCTs published up to October 2020. The total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) concentrations were selected as the primary indicators for dyslipidemia. The results of 13 eligible RCTs showed that probiotic intake could significantly reduce TC (SMD: −0.23, 95% CI: (−0.37, −0.10)) and TG (SMD: −0.27, 95% CI: (−0.44, −0.11)) levels, but did not regulate LDL-C or HDL-C concentrations. Subgroup analysis showed that multispecies probiotics (≥two species), but not single-species probiotics, significantly decreased TC and TG concentrations. Furthermore, powder, but not liquid, probiotics could reduce TC and TG concentrations. This meta-analysis demonstrated that probiotic supplementation is helpful in reducing TC and TG concentrations in T2DM patients. However, more well-controlled trials are needed to clarify the benefits of probiotics on dyslipidemia in T2DM patients.


Rationale
3 Describe the rationale for the review in the context of what is already known. Introduction Introduction Paragraph 4(page 2)

METHODS
Protocol and registration 5 Indicate if a review protocol exists, if and where it can be accessed (e.g., Web address), and, if available, provide registration information including registration number.

No
Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.

Methods
Paragraph 2(page 2-3) Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.

Methods
Paragraph 1(page 2-3) Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.

Methods
Paragraph 1(page 2-3) Study selection 9 State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).

Methods
Paragraph 2(page 2-3) Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.

Paragraph 3(page 3)
Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.

Risk of bias in individual studies
12 Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level), and how this information is to be used in any data synthesis.

RESULTS
Study selection 17 Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.

Results
Paragraph 1 (page 3-4) Figure  1 Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.

Results
Paragraph 2 (page 4-6) Table  1 Risk of bias within studies 19 Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12).

Results
Paragraph 1 (page 7) Figure 2 Results of individual studies 20 For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group (b) effect estimates and confidence intervals, ideally with a forest plot.

Results
Paragraph 3 -7(page 9-11) Synthesis of results 21 Present results of each meta-analysis done, including confidence intervals and measures of consistency. Results Paragraph 3 -7(page 7 -11) Figure 3-6, Table 2 Risk of bias across studies 22 Present results of any assessment of risk of bias across studies (see Item 15

DISCUSSION
Summary of evidence 24 Summarize the main findings including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., healthcare providers, users, and policy makers).