MELATONIN, a hormone primarily known for regulating sleep, has been increasingly investigated for its metabolic effects, including in the context of Type 2 diabetes mellitus (T2D). While previous studies have examined its general impact on diabetes-related outcomes, a focused analysis of its efficacy in individuals with T2D has been lacking. A recent meta-analysis aimed to evaluate the specific role of melatonin supplementation in improving glycaemic control in adults with T2D. The key finding was that melatonin supplementation significantly reduced HbA1c levels, suggesting a potential clinical benefit for long-term glucose regulation.
To conduct this analysis, researchers performed a comprehensive search of PubMed, Cochrane Library, Scopus, Web of Science, and Embase up to September 2024. Only randomised controlled trials (RCTs) involving adults with a diagnosis of T2D and examining the effects of melatonin supplementation were included. The methodological quality of the trials was assessed using the Cochrane Risk of Bias Tool, and data were analysed using RevMan version 5.3 software to determine pooled effects.
The meta-analysis incorporated nine RCTs, comprising a total of 427 participants. Melatonin supplementation was associated with a statistically significant reduction in HbA1c levels compared to placebo, with a mean difference of -0.65 (95% CI: -1.28–-0.02; p=0.04). However, the analysis did not find a statistically significant effect on fasting plasma glucose (FPG) levels (mean difference: -6.40; 95% CI: -15.79–2.99; p=0.18). These findings suggest that while melatonin may contribute to longer-term glycaemic control, its effect on short-term fasting glucose appears minimal.
In conclusion, melatonin supplementation could offer a modest but statistically significant improvement in HbA1c for individuals with T2D, potentially supporting its role as an adjunctive therapy in clinical practice. However, the absence of effect on FPG and the relatively small sample size across trials highlight the need for larger, high-quality studies to confirm these findings. Moreover, variability in dosage, treatment duration, and participant characteristics among the included trials may limit the generalisability of results. Clinicians should consider these factors before recommending melatonin as part of routine diabetes management.
Reference
Lv X et al. The effect of melatonin supplementation on glycemic control in patients with type 2 diabetes. Front Endocrinol (Lausanne). 2025;16:1572613.
