Last updated August 22, 2026
Key finding
Adherence to MD increased after the intervention.
The MEDBIOME study investigated the impact of a Mediterranean diet on microbiota and metabolic outcomes in patients with type 2 diabetes, finding improvements in dietary adherence and several metabolic markers.
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
The MEDBIOME study investigated the impact of a Mediterranean diet on microbiota and metabolic outcomes in patients with type 2 diabetes, finding improvements in dietary adherence and several metabolic markers.
These findings suggest that dietary interventions, such as the Mediterranean diet, can play a crucial role in managing type 2 diabetes by improving metabolic health and gut microbiota composition. This nonpharmacological approach may offer a complementary strategy to traditional diabetes treatments, potentially enhancing patient outcomes and quality of life.
Effectiveness of the intervention remains unclear due to lack of specific p-values. The study did not measure long-term effects beyond the intervention period. Sample size and demographic characteristics may limit generalizability.
Published in
Publication details and source links for this paper.
Shámila I, Marta PS, Miguel V, et al. The Role of Microbiota Modulation by a Nonpharmacological Intervention in Patients with Type 2 Diabetes: The MEDBIOME Study. Nutrients. 2021;13(4):1228. doi:10.3390/nu13041228
Adherence to the Mediterranean diet increased after the intervention.
Bacterial richness improved after 4 weeks of dietary intervention.
Glycated hemoglobin (HbA1c) decreased by 0.67% at the end of the study.
HOMA-IR was reduced at the end of the study.
Evidence network
Understand where this research contributes within the broader evidence network.
This study contributes evidence to Mediterranean diet and Adherence to Mediterranean diet measured using MEDAS-14, Alkaline phosphatase activity assessed in fecal samples, Fasting Plasma Glucose (FPG), and 4 more.
This study contributes evidence to
Primary intervention
Mediterranean diet
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
7
Evidence pairs
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Contributes evidence
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Contributes evidence
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Primary evidence
Evidence topic
matched_intervention_and_outcome
Related evidence
Evidence topic
Save evidence
Core evidence
The primary outcomes reported in this study.
Mediterranean diet → Adherence to Mediterranean diet measured using MEDAS-14
Mediterranean diet → Adherence to Mediterranean diet measured using MEDAS-14
Mediterranean diet → Alkaline phosphatase activity assessed in fecal samples
Mediterranean diet → Alkaline phosphatase activity assessed in fecal samples
Mediterranean diet → Fasting Plasma Glucose (FPG)
Mediterranean diet → Fasting Plasma Glucose (FPG)
Mediterranean diet → Gut microbiota diversity
Mediterranean diet → Gut microbiota diversity
Mediterranean diet → Prevotella to Bacteroides ratio after dietary intervention
Mediterranean diet → Prevotella to Bacteroides ratio after dietary intervention
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Relationships organized using the Dediabetes Evidence Intelligence™ framework.
This study contributes to evidence on Mediterranean diet and HbA1c, Mediterranean diet and Fasting Glucose.
This study contributes to the evidence on the following intervention-outcome relationships.
Diet and Nutrition
Diet and Nutrition
Curated evidence collections and hubs this study is part of.
All studies measuring HbA1c
Measures HbA1c as a key outcome.
All studies on Mediterranean diet
Contributes to Mediterranean diet evidence base.
All studies measuring Fasting Glucose
Measures Fasting Glucose as a key outcome.
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7 results
4 results
7 results
7 results
4 results
Generated from the study's connected evidence using Evidence Intelligence™.
Mediterranean diet may improve HbA1c.
ConsistencyScore™: Results are generally consistent across studies.
Ranked evidence signals
HbA1c
EvidenceScore™ Strong | EvidenceScore™ 84.9 | moderate positive | ConsistencyScore™ Generally Consistent | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Mediterranean diet may improve Insulin resistance.
ConsistencyScore™: Results are consistent across studies.
Ranked evidence signals
Insulin resistance
EvidenceScore™ Strong | EvidenceScore™ 79.0 | moderate positive | ConsistencyScore™ Consistent | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Mediterranean diet may improve Fasting Plasma Glucose (FPG).
ConsistencyScore™: Results are mixed and should be interpreted cautiously.
Ranked evidence signals
Fasting Plasma Glucose (FPG)
EvidenceScore™ Strong | EvidenceScore™ 79.0 | moderate positive | ConsistencyScore™ Mixed | 1 study
Why this answer: This answer is cautious because the available studies report mixed findings.
Limitations
Mediterranean diet appears to improve Adherence to Mediterranean diet measured using MEDAS-14.
ConsistencyScore™: Results are consistent across studies.
Ranked evidence signals
Adherence to Mediterranean diet measured using MEDAS-14
EvidenceScore™ Moderate | EvidenceScore™ 69.0 | strong positive | ConsistencyScore™ Consistent | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
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