Abstract
Insulin resistance (IR) is a pivotal process in various metabolic diseases. The
well-known treatment is lifestyle modification and medication therapy, which may
result in poor compliance and side effects. Melatonin has been suggested to have
a role in glucose metabolism, yet the results across studies have been
inconsistent. Therefore, we performed a systematic review to evaluate the
effects of melatonin supplementation on insulin levels and IR. We searched
PubMed, Embase, Cochrane Central Register of Controlled Trials, and
ClinicalTrials.gov, and identified randomized controlled trials (RCTs) published
prior to August 2020. Articles were reviewed, selected and extracted by two
reviewers independently. In total, 8 RCTs of 376 participants were included.
Data were pooled using a random-effects model, with mean differences (MDs) and
95% confidence intervals (CIs). Our results showed that melatonin
administration significantly reduced insulin levels and homeostasis model
assessment of insulin resistance (HOMA-IR), and increased the quantitative
insulin sensitivity check index (QUICKI). We conclude that melatonin ameliorated
hyperinsulinemia, insulin resistance, and insulin sensitivity, and the results
are an update of a previous meta-analysis. Although more investigations are
required, we clearly provide evidence for the use of melatonin as an adjuvant
treatment for metabolic disorders involving IR.
Key words
melatonin - insulin resistance - insulin levels