Abstract
Background:
Melatonin is increasingly used as a pharmacological sleep-aid but it is also emerging as a regulator of glucose homeostasis. Yet, previous research has been ambiguous with reports of both positive and negative effects of melatonin on glucose metabolism.
Objectives:
To assess the effect of daily treatment with melatonin on fasting glucose, insulin, insulin sensitivity, and HbA1c levels.
Data sources:
MEDLINE, EMBASE, CENTRAL, clinicaltrials.gov, and clinicaltrialsregister.eu were systematically searched.
Eligibility criteria, participants and interventions:
All randomized, placebo-controlled studies with melatonin treatment were assessed. We included studies with daily melatonin treatment (≥ two weeks) of healthy adults or patients with metabolic diseases.
Methods:
Hedges' g differences were calculated for the metabolic parameters of the included studies, heterogeneity was assessed with chi2 and I 2 tests, and meta-analyses were performed with the random-effects model.
Results:
Long-term treatment with melatonin did not change fasting glucose significantly compared with placebo (g -0.07 [-0.22-0.08], n=603), but it reduced fasting insulin levels slightly (g -0.27 [-0.50 - -0.04], n=278) and trended towards reduced insulin resistance (HOMA-IR) (g -0.20 [-0.44 - 0.03], n=278). HbA1c levels were largely unaffected by melatonin treatment compared with placebo (g 0.14 [-0.19 - 0.46], n=142).
Conclusion:
With the available literature, melatonin seems to be a glucose-metabolic safe sleep-aid in patients with metabolic diseases and in healthy adults. It may even have beneficial glucose-metabolic effects as fasting insulin levels were reduced in this meta-analysis, but the confidence intervals of the meta-analyses are wide, underscoring the need for further research within this field. This article is protected by copyright. All rights reserved.
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