The impact of probiotics or synbiotics on individuals with type 1 diabetes mellitus (T1DM): a systematic review and meta-analysis
In brief
Probiotics and synbiotics lowered HbA1c by 0.58 percentage points in type 1 diabetes
A meta-analysis of 10 randomized trials found probiotics or synbiotics were linked to lower HbA1c and fasting blood sugar, but did not significantly change insulin requirements or C-peptide. The HbA1c reduction could matter if sustained; larger, higher-quality trials are needed to confirm the benefit and clarify which products work.
- Journal
- BMC endocrine disorders (Q1)
- Published
- 7 August 2026
- Study design
- Systematic review / meta-analysis of RCTs
- Evidence level
- Level 1, High (CEBM 1a)
- Authors
- Sina Sohrabizadeh, Mehrad Namazee, Mohammad Erfan Lotfi, Seyed Amirhossein Tabatabaei, Saghar Elmi, Jeyran Ostovarfar
- PMID
- 42989287
- DOI
- 10.1186/s12902-026-02453-1
Why clinicians should know about it
- Picked for Immunology and Allergy (paper of the day, 7 November 2026): Randomized-trial synthesis on autoimmune type 1 diabetes intervention
Abstract
INTRODUCTION: Type 1 Diabetes Mellitus (T1DM) is a chronic autoimmune condition characterized by insulin deficiency. Probiotics and synbiotics are believed to impact glycemic control. This study aims to evaluate their effects on individuals with T1DM. METHODS: A systematic search was conducted from inception to January 2026 in Cochrane Central, Web of Science, Scopus, and PubMed, with additional screening of gray literature and reference lists. Randomized controlled trials evaluating probiotics or synbiotics in individuals with type 1 diabetes mellitus (T1DM) were included. Risk of bias was assessed using the Cochrane ROB-2 tool. Data were synthesized using weighted mean difference (WMD) with 95% confidence intervals under a random-effects model in STATA-17. Subgroup, sensitivity, and publication bias analyses were also performed. RESULTS: From 2,722 records, 10 randomized controlled trials were included. Meta-analysis showed that probiotics or synbiotics significantly reduced HbA1c (WMD = -0.58%, 95% CI [-1.00, -0.17]) and fasting blood sugar (WMD = -43.34 mg/dL, 95% CI [-81.71, -4.96]) compared with controls. No significant effects were observed for C-peptide (WMD = -0.03 ng/mL, 95% CI [-0.11, 0.05]) or insulin requirement (WMD = -0.09 U/kg/day, 95% CI [-0.19, 0.01]). A significant reduction was found in total cholesterol (WMD = -7.92, 95 mg/dL CI [-15.73, -0.12]), whereas no significant changes were found for CRP, TG, HDL, LDL, or TNF-α. CONCLUSION: Probiotics or synbiotics may improve glycemic control in T1DM, particularly by reducing HbA1c and fasting blood sugar. The observed HbA1c improvement may be clinically meaningful if sustained. However, evidence for effects on beta-cell function, insulin requirement, inflammatory markers, and most lipid outcomes remains limited. Larger, high-quality trials with standardized interventions are needed to confirm these findings. CLINICAL TRIAL NUMBER: Not applicable.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.