Does Melatonin help blood sugar? (Grade C evidence)
Melatonin may modestly help blood sugar in specific populations (Grade C, low certainty), especially in adults. Dose range: varies across trials.
Bottom line. Melatonin may modestly help blood sugar in specific populations (Grade C, low certainty), especially in adults. Dose range: varies across trials. [1 RCT]
- Direction
- benefit
- Magnitude
- Meta-analysis of 12 RCTs: melatonin supplementation significantly reduced fasting glucose and improved insulin sensitivity (QUICKI index), but had no significant effect on insulin levels, HOMA-IR, or HbA1c. A partial biomarker signal on fasting glucose specifically, not comprehensive glycemic control.
- Grade
- C
- Certainty
- low
- Clinical meaning
- small but potentially useful
- Who it applies to
- adults
- Dose / form studied
- Safety
- uncertain_with_ssri
- The one limitation
- Sample sizes are small in most included trials; effect sizes may shrink with larger studies.
Reviewed · Evidence last changed · Claim clm_ec_b10-mel-blood-sugar v1
⚠ Safety in context
- uncertainwith SSRI: Melatonin with an SSRI: possible additive sedation; evidence is thin. full interaction →
Grade C / low: hints of benefit in small trials; a well-run RCT could easily push this to B or to null.
Who it works for
Best-studied in adults. Effective doses cluster around varies across trials.
Evidence
| Study | Design | Cite |
|---|---|---|
| The Effects of Melatonin Supplementation on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. | peer-reviewed | PMID:30396207 |
Why this grade
Reasoning trace
Grade C at low certainty. The grade reflects the direction and size of the effect across the 1 publishable source above; certainty reflects heterogeneity, sample sizes, and design quality. What would move it upward: additional well-powered RCTs in the target population that replicate the effect at similar doses. What would move it down: a large null trial, discovery of publication bias, or a retraction of a keystone study.
Dose & form
Studied intake: varies across trials.
How it stacks up for blood sugar
- Melatonin vs Berberine for blood sugar — Berberine Grade B
- Melatonin vs Magnesium for blood sugar — Magnesium Grade C
- Melatonin vs Myo-Inositol for blood sugar — Myo-Inositol Grade B
- Melatonin vs Ashwagandha for blood sugar — Ashwagandha Grade C
- Melatonin vs Omega-3 for blood sugar — Omega-3 Grade B
- Melatonin vs Creatine for blood sugar — Creatine Grade C
- All interventions graded for blood sugar →
Grade history
No grade changes yet. Initial grade assigned; re-reviewed on every 6 months (Grade C+) — next review by . Methodology v1.
Re-review cadence: every 6 months (Grade C+) · next scheduled by · methodology v1.
Frequently asked
How long does Melatonin take to work for blood sugar?
Trials of Melatonin for blood sugar typically report effects within 2–4 weeks, though individual response varies. Studies rarely find benefit inside 1 week for chronic outcomes.
What dose was used in studies of Melatonin for blood sugar?
Studied doses for Melatonin in blood sugar trials cluster around varies across trials. See the dose block for the specific range and how it varies by form.
Does Melatonin work for blood sugar if I'm not deficient?
The effect concentrates in adults. If your baseline is normal, expect a smaller effect than the trial averages.
Melatonin or the next-best alternative for blood sugar?
See the compare block above for the head-to-head with the most-cited alternative. Grade + certainty differences matter more than any single trial.
Related
What this is — and is not
- Evidence description
- Meta-analysis of 12 RCTs: melatonin supplementation significantly reduced fasting glucose and improved insulin sensitivity (QUICKI index), but had no significant effect on insulin levels, HOMA-IR, or HbA1c. A partial biomarker signal on fasting glucose specifically, not comprehensive glycemic control.
- Substrate's interpretation
- Grade C at low certainty — the direction and size the studies converge on, as our reading of the corpus.
- Discuss with a clinician
- If you're on medication or have a condition that changes the calculus, bring the interaction & population blocks above to your pharmacist or prescriber before deciding.
- Individualized medical advice
- Not provided here or on any Substrate surface (API, agent tool, embed) — see YMYL policy.
Cite this page
Reuse under CC-BY 4.0 with attribution to evidencebased.info.
Plain-text citation
Substrate. Does Melatonin help blood sugar? (Grade C). https://evidencebased.info/interventions/melatonin/blood-sugar. Updated 2026-07-16.
BibTeX
@misc{substrate_smelatoninbloodsugar,
author = {Substrate editorial},
title = {Does Melatonin help blood sugar?},
year = {2026},
url = {https://evidencebased.info/interventions/melatonin/blood-sugar},
note = {Grade C, evidencebased.info}
}Found something wrong on this page? Report an error →