Melatonin Impairs Glucose Tolerance, First-Phase Insulin Secretion, and Insulin Feedback Inhibition; Interaction With MTNR1B Diabetes Risk Variant
Authors' conclusion
These findings identify blunted β-cell responsivity to glucose and dysregulated insulin negative feedback as key mechanisms linking melatonin signaling to diabetes risk.
Study context
- Population
- Healthy participants of European ancestry: 10 MTNR1B G-allele risk carriers and 11 noncarriers; 5-day laboratory protocolcrossover
- Participants
- 21 participants
- Comparison
- 5 mg oral melatonin vs placebo, by MTNR1B genotype
Methodological detailsdouble-blind, placebo-controlled, crossover
- Double-blind
- Placebo-controlled
- Crossover
Primary result
As reported in the abstract
Melatonin vs PlaceboEstimate (95% CI)P value
Risk allele carriers; worsened glucose tolerance
difference in glucose tolerance 11.7 %(1.0–22.3)
Padj < 0.05Risk allele carriers; reduced early C-peptide response
difference in early C-peptide response −19.2 %(−33.9 to −1.2)
Padj < 0.05- Carriers: suppression of glucose-stimulated first-phase β-cell responsivity (Padj = 0.0003)
- 40% (−52.4 to −24.3)
- Carriers: slower insulin-induced decline in second-phase insulin secretion rate (Padj = 0.001)
- 64.3% [23.1-119.2]
Further findings
Events
| Outcome | Melatonin | Placebo | P value |
|---|---|---|---|
| Exogenous insulin-induced hypoglycemia events, risk carriers | 0 | 7 | P = 0.001 |
Exogenous insulin-induced hypoglycemia events, risk carriers
- Not prevented in noncarriers
Original publication
Melatonin Impairs Glucose Tolerance, First-Phase Insulin Secretion, and Insulin Feedback Inhibition; Interaction With MTNR1B Diabetes Risk Variant. Diabetes Care. Published 25 June 2026. doi:10.
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