Year: 2025
Type: review
Study designs: Systematic Review, Meta-Analysis
Abstract: Objective: Data on the effects of melatonin on insulin sensitivity and resistance is limited and controversial. This meta-analysis aims to investigate the impact of melatonin on insulin resistance and insulin sensitivity. Methods: Following PRISMA guidelines, a systematic search was conducted in PubMed, Scopus, and Google Scholar databases up to March 29, 2025. Randomized controlled trials (RCTs) evaluating melatonin’s effects on glucose metabolism parameters were included. Data extraction and quality assessment were performed using Joanna Briggs Institute (JBI) checklists. Statistical analyses utilized random-effects models to account for heterogeneity. Results: Eleven RCTs involving 393 participants were analyzed. Pooled estimates showed no significant effect of melatonin on insulin resistance (homeostatic model assessment for insulin resistance: weighted mean difference (HOMA-IR: WMD) = −0.15, 95% CI: −0.50 to 0.19, P = .38). Insulin sensitivity outcomes demonstrated a non-significant reduction (WMD = −0.51, 95% CI: −0.81 to −0.21, P = .89). Substantial heterogeneity was observed (I2 = 85.4%), attributed to variability in melatonin dosing (1-40 mg/day), intervention durations (acute to 24 weeks), and participant characteristics (healthy vs. type 2 diabetes mellitus). Conclusion: Melatonin supplementation did not significantly improve insulin resistance and showed a non-significant trend toward reduced insulin sensitivity, particularly at higher doses. High heterogeneity underscores the need for cautious interpretation and individualized clinical application. Future large-scale RCTs should prioritize subgroup analyses by dose, administration timing, and baseline metabolic status to clarify melatonin’s role in glucose regulation. Cite this article as: Rahimi A, Kalhor M, Azad R, et al. Impact of melatonin supplementation on insulin resistance and sensitivity: A meta-analysis. Endocrinol Res Pract. Published online November 27, 2025. doi:10.5152/erp.2025.25646.
Authors: Arash Rahim, Mahdie Kalhor, Rosa Azad, Amir Mohammad Karami, Aydin Hassanpour Adeh, Fatemeh Eslampanah, Yasamin Moeinipour, Aida Bakhshi, Samira Peiravi, Mahdyieh Naziri, Niloofar Deravi
Institutions: Shahid Beheshti University, Shahid Beheshti University of Medical Sciences, Alborz University of Medical Sciences, Isfahan University of Medical Sciences, Tehran University of Medical Sciences, Islamic Azad University of Tabriz, Kermanshah University of Medical Sciences, Mashhad University of Medical Sciences, Ghaem Hospital, Iran University of Medical Sciences
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W4416768397