Effects of daily administration of melatonin before bedtime on fasting insulin, glucose and insulin sensitivity in healthy adults and patients with metabolic diseases. A systematic review and meta-analysis
Esben S. Lauritzen, Clinical Endocrinology 09 August 2021
Background
Melatonin is increasingly used as a pharmacological sleep aid but it is also emerging as a regulator of glucose homoeostasis. 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 haemoglobin A1c (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 (≥2 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 χ2 and I2 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 to 0.08], n = 603) but it reduced fasting insulin levels slightly (g: −0.27 [−0.50 to −0.04], n = 278) and trended towards reduced insulin resistance (HOMA-IR) (g: −0.20 [−0.44 to 0.03], n = 278). HbA1c levels were largely unaffected by melatonin treatment compared with placebo (g: 0.14 [−0.19 to 0.46], n = 142).
Conclusions
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.
L'administration diurne de mélatonine a été associée dans plusieurs études à une diminution de la sensibilité à l'insuline
La prise de mélatonine avant le coucher chez les adultes en bonne santé et chez les patients atteints de maladies métaboliques semble être sans danger en ce qui concerne le métabolisme du glucose et peut même être bénéfique puisque les niveaux d'insuline à jeun ont été significativement diminués, suggérant un effet positif sur la sensibilité à l'insuline.