Resumen de Investigación
Analyzed using Evidence Intelligence™

Melatonin shows little effect on glycemic control in type 2 diabetes

Última actualización 16 de agosto de 2026

Key finding

FBG levels in the placebo arm decreased significantly at the end of trial.

This study investigated the effect of melatonin on glycemic control in patients with type 2 diabetes, finding no significant differences between melatonin and placebo groups.

Quick read

Study at a glance

The essential study design details in one scan.

EvidenceScore™

Moderate

Study type

RCTs

Follow-up

Short-Term (≤3 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 effect of melatonin on glycemic control in patients with type 2 diabetes, finding no significant differences between melatonin and placebo groups.

Clinical relevance

Understanding the effectiveness of melatonin for glycemic control is crucial for managing type 2 diabetes. This study suggests that melatonin may not be a beneficial treatment option for improving blood sugar levels, guiding clinicians in their treatment choices.

Keep in mind

The study may have limited generalizability due to specific inclusion criteria. Sample size and duration may not have been sufficient to detect subtle effects. Unmeasured confounders could have influenced the outcomes.

Published in

Referencia de la Revista

Publication details and source links for this paper.

Amir F, Maryam T, Noushin SA, et al. The Effect of Melatonin on Glycemic Control in Patients with Type 2 Diabetes: A Triple-Blind, Placebo-Controlled Trial. Iranian Journal of Pharmaceutical Research : IJPR. 2019;18(Suppl1):258-268. doi:10.22037/ijpr.2019.112011.13485

Efectos Principales

No significant changes in fasting blood glucose levels between melatonin and placebo groups (p=0.897).

No significant changes in HbA1c levels between groups (p=0.912).

FBG levels in the placebo group decreased significantly at the end of the trial.

Evidence network

How this study fits

Understand where this research contributes within the broader evidence network.

Evidence Context

This study contributes evidence to Melatonin and C-reactive protein, Fasting blood sugar (FBS), HbA1c, and 2 more.

Primary intervention

Melatonin

Primary outcomes

  • C-reactive protein
  • Fasting blood sugar (FBS)
  • HbA1c

Evidence relationships

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

5
Evidence pairs
5
Relationships
3
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: 68

3

Related topics

5

Evidence pairs

773

Related studies

High relevance in at least one topic

Why it is useful

  • Contributes to 5 evidence relationships
  • Includes primary outcome data
  • Linked to 3 direct semantic evidence topics

Topic contributions

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

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Evidencia principal

Tema de evidencia

Glycemic Control

matched_outcome

Evidencia relacionada

Tema de evidencia

HbA1c Reduction

Guardar evidencia

Core evidence

Study findings

The primary outcomes reported in this study.

C-reactive protein

Melatonin → C-reactive protein

Melatonin → C-reactive protein

Evidence Intelligence™
EvidenceScore™
Moderate
Score 69 · Based on 2 studies
ImpactScore™
50
Neutral
ConsistencyScore™
100
consistent
Estudios de apoyo: Basado en 2 estudios
Add to Evidence Tracker

Fasting blood sugar (FBS)

Melatonin → Fasting blood sugar (FBS)

Melatonin → Fasting blood sugar (FBS)

Evidence Intelligence™
EvidenceScore™
Emerging
Score 59 · Based on 1 study
ImpactScore™
50
Neutral
ConsistencyScore™
unclear
Not enough independent studies
Estudios de apoyo: Basado en 1 estudio
Add to Evidence Tracker

HbA1c

Melatonin → HbA1c

Melatonin → HbA1c

Evidence Intelligence™
EvidenceScore™
77
Strong
ImpactScore™
67
Slightly Positive
ConsistencyScore™
67
generally_consistent
Estudios de apoyo: Basado en 3 estudios
Add to Evidence Tracker

Insulin resistance

Melatonin → Insulin resistance

Melatonin → Insulin resistance

Evidence Intelligence™
EvidenceScore™
Moderate
Score 69 · Based on 2 studies
ImpactScore™
50
Neutral
ConsistencyScore™
100
consistent
Estudios de apoyo: Basado en 2 estudios
Add to Evidence Tracker

Insulin sensitivity

Melatonin → Insulin sensitivity

Melatonin → Insulin sensitivity

Evidence Intelligence™
EvidenceScore™
Moderate
Score 69 · Based on 2 studies
ImpactScore™
38
Slightly Negative
ConsistencyScore™
35
mixed
Estudios de apoyo: Basado en 2 estudios
Add to Evidence Tracker

Evidence Library

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evidence suggest

La Evidencia Sugiere

  • No significant difference in fasting blood glucose between melatonin and placebo (p=0.897).
  • HbA1c levels showed no significant change between groups (p=0.912).
  • Placebo group experienced a significant decrease in fasting blood glucose levels.
who this applies

A quién se aplica

  • Adults diagnosed with type 2 diabetes.
  • Participants who were not on melatonin prior to the study.
keep in mind

Tener en Cuenta

  • Results may not apply to all populations with diabetes.
  • The study did not assess long-term effects of melatonin.
  • Further research is needed to explore potential benefits in different contexts.
between the lines

Entre Líneas

  • The study may have limited generalizability due to specific inclusion criteria.
  • Sample size and duration may not have been sufficient to detect subtle effects.
  • Unmeasured confounders could have influenced the outcomes.

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 Melatonin and HbA1c, Melatonin and Inflammatory Markers.

Relaciones de evidencia relacionadas

Explore in Evidence Explorer

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

Questions answered by this study

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

Does Melatonin improve HbA1c?

Strong Evidence

Melatonin may improve HbA1c.

ConsistencyScore™: Results are generally consistent across studies.

Ranked evidence signals

  1. 1

    HbA1c

    EvidenceScore™ Strong | EvidenceScore™ 77.4 | weak positive | ConsistencyScore™ Generally Consistent | 1 study

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

Limitations

  • Only one supporting study is available.
  • Population details are unavailable.
1 supporting studyUpdated: Aug 2026

Does Melatonin improve c-reactive protein?

Moderate Evidence

Current evidence does not show a clear benefit of Melatonin for C-reactive protein.

ConsistencyScore™: Results are consistent across studies.

Ranked evidence signals

  1. 1

    C-reactive protein

    EvidenceScore™ Moderate | EvidenceScore™ 69.0 | neutral | ConsistencyScore™ Consistent | 1 study

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

Limitations

  • Only one supporting study is available.
  • Population details are unavailable.
1 supporting studyUpdated: Aug 2026

Does Melatonin improve insulin resistance?

Moderate Evidence

Current evidence does not show a clear benefit of Melatonin for Insulin resistance.

ConsistencyScore™: Results are consistent across studies.

Ranked evidence signals

  1. 1

    Insulin resistance

    EvidenceScore™ Moderate | EvidenceScore™ 69.0 | neutral | ConsistencyScore™ Consistent | 1 study

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

Limitations

  • Only one supporting study is available.
  • Population details are unavailable.
1 supporting studyUpdated: Aug 2026

Does Melatonin improve insulin sensitivity?

Moderate Evidence

Melatonin may worsen Insulin sensitivity or be associated with harm.

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

Evidence caveat: The available evidence reports mixed findings.

Ranked evidence signals

  1. 1

    Insulin sensitivity

    EvidenceScore™ Moderate | EvidenceScore™ 69.0 | weak negative | 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.
  • Population details are unavailable.
1 supporting studyUpdated: Aug 2026
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