Research Summary

Analyzed using Evidence Intelligence™

Zinc supplementation shows little effect on glycemic control in Type 2 diabetes

Last updated September 10, 2026

Key finding

There were no significant differences before and after the intervention in the FBG between the two groups.

This study investigated the effects of zinc sulfate supplementation on glycemic control in patients with type 2 diabetes, finding no significant differences in key outcomes.

Quick read

Study at a glance

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

What this paper says

A plain-language read of the study’s main message and where it applies.

Study focus

This study investigated the effects of zinc sulfate supplementation on glycemic control in patients with type 2 diabetes, finding no significant differences in key outcomes.

Clinical relevance

Understanding the effectiveness of zinc supplementation in managing diabetes is crucial for developing comprehensive treatment plans. This study's findings suggest that zinc may not be a beneficial addition to diabetes management strategies, highlighting the need for further research into alternative interventions.

Keep in mind

Limited sample size may affect the generalizability of results. Short duration of the study may not capture long-term effects. Lack of significant findings raises questions about the intervention's efficacy.

Published in

Journal Reference

Publication details and source links for this paper.

Mehrab S, Sara JN, Fatemeh BI, et al. Effects of Zinc Supplementation on Glycemic Control in Patients with Type 2 Diabetes: A Randomized Controlled Trial. Health Science Reports. 2025;8(1):e70375. doi:10.1002/hsr2.70375

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Main Effects

No significant differences in fasting blood glucose between intervention and control groups.

No significant changes in glycated hemoglobin levels after zinc supplementation.

Zinc levels did not differ significantly between the two groups.

Body weight increased in the intervention group but not significantly compared to the control.

Evidence network

How this study fits

Understand where this research contributes within the broader evidence network.

Evidence Context

This study contributes evidence to Zinc supplementation and Body weight, Diastolic blood pressure, Fasting Blood Glucose (FBG), and 4 more.

This study contributes evidence to

Intervention

Zinc supplementation

Outcome

Body weight

Evidence topic

Blood Pressure

Primary intervention

Zinc supplementation

Primary outcomes

Body weight
Diastolic blood pressure
Fasting Blood Glucose (FBG)

Evidence topics

Blood Pressure Weight Loss Body Composition HbA1c Reduction

Primary intervention

Zinc supplementation

Primary outcomes

Body weight Diastolic blood pressure Fasting Blood Glucose (FBG)

Evidence relationships

Intervention and outcome relationships this study adds to the evidence network.

Evidence pairs

Relationships

Evidence topics

contributes_evidence

Editorial context

Why this study matters

See why this paper is useful beyond its individual results.

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.

Moderate contributionModerate confidenceNetwork score: 72

Why it is useful

Contributes to 7 evidence relationships
Includes primary outcome data
Linked to 4 direct semantic evidence topics

Topic contributions

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

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Primary evidence

Evidence topic

Blood Pressure

matched_outcome

Related evidence

Evidence topic

Weight Loss

Save evidence

Core evidence

Study findings

The primary outcomes reported in this study.

Body weight

Zinc supplementation → Body weight

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

Diastolic blood pressure

Zinc supplementation → Diastolic blood pressure

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

Fasting Blood Glucose (FBG)

Zinc supplementation → Fasting Blood Glucose (FBG)

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

HbA1c

Zinc supplementation → HbA1c

Evidence Intelligence™

EvidenceScore™: Moderate; Score 69 · Based on 2 studies
ImpactScore™: 75; Positive
ConsistencyScore™: 35; mixed

Based on 2 studies

Add to Evidence Tracker

Systolic blood pressure

Zinc supplementation → Systolic blood pressure

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

Waist circumference

Zinc supplementation → Waist circumference

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

Zinc

Zinc supplementation → Zinc

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

Add to Evidence Tracker

Evidence Library

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Evidence Suggest

Zinc supplementation did not significantly alter fasting blood glucose levels.
No significant changes in glycated hemoglobin were observed.
Body weight increased in the intervention group, but not significantly.

Who this applies to

Adults diagnosed with type 2 diabetes.
Patients seeking alternative treatments for glycemic control.

Keep in Mind

Results may not apply to populations outside the study sample.
Further research is needed to explore other potential benefits of zinc.
The study's short duration limits understanding of long-term effects.

Between the Lines

Limited sample size may affect the generalizability of results.
Short duration of the study may not capture long-term effects.
Lack of significant findings raises questions about the intervention's efficacy.

Evidence Library

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Connected Evidence

Explore related studies, evidence collections, and research questions.

Relationships organized using the Dediabetes Evidence Intelligence™ framework.

This study contributes to evidence on Zinc supplementation and HbA1c, Zinc supplementation and Body Weight.

Related evidence relationships

Explore in Evidence Explorer

This study contributes to the evidence on the following intervention-outcome relationships.

Supplements

Detailed evidence

Zinc supplementation → HbA1c

Supplements

Evidence Intelligence™

EvidenceScore™: Moderate; Score 69 · Based on 2 studies
ImpactScore™: 75; Positive
ConsistencyScore™: 35; mixed

Based on 2 studies

View evidence

Supplements

Detailed evidence

Zinc supplementation → Body Weight

Supplements

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

View evidence

Supplements

Detailed evidence

Zinc supplementation → Blood Pressure

Supplements

Evidence Intelligence™

EvidenceScore™: Emerging; Score 59 · Based on 1 study
ImpactScore™: 50; Neutral
ConsistencyScore™: unclear; Not enough independent studies

Based on 1 study

View evidence

Included in these evidence collections

Curated evidence collections and hubs this study is part of.

HbA1c Evidence Hub

All studies measuring HbA1c

2 studies

outcome_hub

Measures HbA1c as a key outcome.

Zinc supplementation Evidence Hub

All studies on Zinc supplementation

2 studies

intervention_hub

Contributes to Zinc supplementation evidence base.

Blood Pressure Evidence Hub

All studies measuring Blood Pressure

1 studies

outcome_hub

Measures Blood Pressure as a key outcome.

Body Weight Evidence Hub

All studies measuring Body Weight

1 studies

outcome_hub

Measures Body Weight as a key outcome.

Recent Diabetes Research

Latest published studies

recency_collection

Published within the last 2 years.

Explore more in Evidence Explorer

Jump to pre-filtered views in Evidence Explorer.

All studies on Zinc supplementation and HbA1c

Intervention: Zinc supplementationOutcome: HbA1c

2 results

All studies on Zinc supplementation and Body weight

Intervention: Zinc supplementationOutcome: Body weight

1 results

All studies on Zinc supplementation

Intervention: Zinc supplementation

2 results

All studies measuring HbA1c

Outcome: HbA1c

2 results

All studies measuring Body weight

Outcome: Body weight

1 results

Questions answered by this study

Generated from the study's connected evidence using Evidence Intelligence™.

Does Zinc supplementation lower HbA1c?

Moderate Evidence

Zinc supplementation may lower HbA1c.

ConsistencyScore™: Results are mixed and should be interpreted cautiously.

Evidence caveat: The available evidence reports mixed findings.

Ranked evidence signals

1
HbA1c
EvidenceScore™ Moderate | EvidenceScore™ 69.0 | moderate positive | ConsistencyScore™ Mixed | 1 study

Why this answer: This answer is cautious because the available studies report mixed findings.

Limitations

Only one supporting study is available.

View Full Evidence

Does Zinc supplementation affect body weight?

Emerging Evidence

Current evidence does not show a clear effect of Zinc supplementation on body weight.

ConsistencyScore™: Consistency cannot yet be determined from the available evidence.

Ranked evidence signals

1
Body weight
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study

Why this answer: This answer is based on a single supporting study.

Limitations

Only one supporting study is available.

View Full Evidence

Does Zinc supplementation improve diastolic blood pressure?

Emerging Evidence

Current evidence does not show a clear benefit of Zinc supplementation for diastolic blood pressure.

ConsistencyScore™: Consistency cannot yet be determined from the available evidence.

Ranked evidence signals

1
Diastolic blood pressure
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study

Why this answer: This answer is based on a single supporting study.

Limitations

Only one supporting study is available.

View Full Evidence

Does Zinc supplementation improve fasting blood glucose (FBG)?

Emerging Evidence

Current evidence does not show a clear benefit of Zinc supplementation for fasting blood glucose (FBG).

ConsistencyScore™: Consistency cannot yet be determined from the available evidence.

Ranked evidence signals

1
Fasting Blood Glucose (FBG)
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study

Why this answer: This answer is based on a single supporting study.

Limitations

Only one supporting study is available.

View Full Evidence

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Next steps

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Evidence topics

Follow the topics this study contributes to.

Blood Pressure Evidence Hub Weight Loss Evidence Hub Body Composition Evidence Hub HbA1c Reduction Evidence Hub

Explore in Evidence Explorer

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All studies on Zinc supplementation and HbA1c All studies on Zinc supplementation and Body weight All studies on Zinc supplementation and Diastolic blood pressure All studies on Zinc supplementation and Fasting Blood Glucose (FBG)

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