Last updated June 19, 2026
Key finding
Probiotic group reported 26% vs. 52% in placebo group (p < 0.05).
This study investigated whether multi-strain probiotic supplementation enhances the metabolic effects of metformin in women with elevated HOMA-IR, finding no significant improvements.
Quick read
The essential study design details in one scan.
EvidenceScore™
Moderate
Study type
RCTs
Follow-up
Medium-Term (3–12 mo)
Risk of bias
Some Concerns
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Plain-language summary
A plain-language read of the study’s main message and where it applies.
Study focus
This study investigated whether multi-strain probiotic supplementation enhances the metabolic effects of metformin in women with elevated HOMA-IR, finding no significant improvements.
Understanding the interaction between probiotics and diabetes medications like metformin is crucial for optimizing treatment strategies. This study suggests that while probiotics may alleviate some gastrointestinal side effects, they do not improve metabolic outcomes, which is important for clinicians considering adjunct therapies for patients with insulin resistance.
Limited to women with elevated HOMA-IR, affecting generalizability. Small sample size may limit the robustness of findings. Short duration of the study may not capture long-term effects.
Published in
Publication details and source links for this paper.
Marzena R, Agnieszka B, Katarzyna M, et al. Multi-strain Probiotic Supplementation Does Not Enhance Metabolic Efficacy of Metformin in Women with Elevated HOMA-IR. Frontiers in Endocrinology. 2026;17:1765741. doi:10.3389/fendo.2026.1765741
Probiotic group reported 26% gastrointestinal symptoms vs. 52% in placebo (p < 0.05).
Probiotic group reported 18% abnormal stool frequency vs. 51% in placebo (p < 0.05).
No significant differences in fasting plasma glucose or insulin resistance between groups.
Evidence network
Understand where this research contributes within the broader evidence network.
This study contributes evidence to Multi-species synbiotic (12 probiotic strains + FOS prebiotic) and Abnormal stool frequency, Fasting Plasma Glucose (FPG), Gastrointestinal symptoms frequency, and 4 more.
This study contributes evidence to
Primary intervention
Multi-species synbiotic (12 probiotic strains + FOS prebiotic)
Primary outcomes
Intervention and outcome relationships this study adds to the evidence network.
Editorial context
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Evidence network role
This section describes how the study fits into the current evidence network. It does not determine whether an intervention works on its own.
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Related topics
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Evidence pairs
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Contributes evidence
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Contributes evidence
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Contributes evidence
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Primary evidence
Evidence relationship
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Evidence relationship
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Evidence relationship
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Core evidence
The primary outcomes reported in this study.
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Abnormal stool frequency
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Abnormal stool frequency
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Fasting Plasma Glucose (FPG)
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Fasting Plasma Glucose (FPG)
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Gastrointestinal symptoms frequency
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Gastrointestinal symptoms frequency
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Hard or lumpy stools
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Hard or lumpy stools
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Insulin resistance
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Insulin resistance
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Retinol-Binding Protein 4 (RBP4)
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Retinol-Binding Protein 4 (RBP4)
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Total cholesterol
Multi-species synbiotic (12 probiotic strains + FOS prebiotic) → Total cholesterol
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Relationships organized using the Dediabetes Evidence Intelligence™ framework.
This study contributes to evidence on Probiotics and Synbiotics and Fasting Glucose, Probiotics and Synbiotics and Adipokine and Angiogenic Markers.
This study contributes to the evidence on the following intervention-outcome relationships.
Supplements
Curated evidence collections and hubs this study is part of.
All studies measuring Fasting Glucose
Measures Fasting Glucose as a key outcome.
All studies on Probiotics and Synbiotics
Contributes to Probiotics and Synbiotics evidence base.
All studies measuring Adipokine and Angiogenic Markers
Measures Adipokine and Angiogenic Markers as a key outcome.
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Published within the last 2 years.
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3 results
2 results
3 results
3 results
2 results
Generated from the study's connected evidence using Evidence Intelligence™.
Probiotics and Synbiotics may improve Fasting Glucose.
ConsistencyScore™: Results are generally consistent across studies.
Ranked evidence signals
Fasting Plasma Glucose (FPG)
EvidenceScore™ Strong | EvidenceScore™ 79.0 | moderate positive | ConsistencyScore™ Generally Consistent | 1 study
Why this answer: This answer is based on 11 supporting studies with generally consistent results and a positive effect signal.
Limitations
Probiotics and Synbiotics may improve Insulin Resistance.
ConsistencyScore™: Results are generally consistent across studies.
Ranked evidence signals
Insulin resistance
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on 5 supporting studies with generally consistent results and a positive effect signal.
Limitations
Probiotics and Synbiotics may improve Adipokine and Angiogenic Markers.
ConsistencyScore™: Results are generally consistent across studies.
Ranked evidence signals
Total cholesterol
EvidenceScore™ Moderate | EvidenceScore™ 69.0 | moderate positive | ConsistencyScore™ Mixed | 1 study
Retinol-Binding Protein 4 (RBP4)
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on 11 supporting studies with generally consistent results and a positive effect signal.
Limitations
Probiotics and Synbiotics appears to improve Gastrointestinal Adverse Events.
ConsistencyScore™: Consistency cannot yet be determined from the available evidence.
Ranked evidence signals
Abnormal stool frequency
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | strong positive | ConsistencyScore™ Unclear | 1 study
Gastrointestinal symptoms frequency
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | strong positive | ConsistencyScore™ Unclear | 1 study
Hard or lumpy stools
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | strong positive | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
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