Melatonin supplementation modestly lowers blood sugar and triglycerides in kidney transplant recipients

Sleep Evidence: RCT · n=84 · randomized double-blind placebo-controlled trial 2026-09-02

A randomized controlled trial of 84 kidney transplant recipients found that 6 mg/day melatonin for three months was associated with small reductions in HbA1c and triglycerides compared to placebo, though fasting blood sugar effects were not statistically significant between groups.

Kidney transplant recipients often develop metabolic complications—including elevated blood sugar and lipid abnormalities—that increase mortality risk. This randomized, double-blind, placebo-controlled trial tested whether melatonin, known for both sleep regulation and antioxidant properties, could improve these markers.

Researchers at Labbafinejad Hospital in Tehran enrolled 84 adult transplant recipients (≥6 months post-transplant), randomly assigning 42 to 6 mg/day melatonin and 42 to placebo for three months. In the melatonin group, fasting blood sugar fell by a median of 6.5 mg/dL and HbA1c (a 3-month glucose average) dropped 0.25 units; both rose in the placebo group. When adjusted for baseline values and confounders, the between-group difference favored melatonin for HbA1c (−0.30%; 95% CI: −0.59 to −0.01; P<0.001), but the fasting glucose difference was not statistically significant (β=−2.61 mg/dL; P=0.283). Triglycerides fell 16 mg/dL in the melatonin arm versus rising 13.5 mg/dL in placebo (adjusted effect −23.77 mg/dL; P=0.032). Blood pressure and kidney function showed no significant changes. A key limitation is the short 3-month window; longer-term effects remain unknown.

Takeaway

Melatonin supplementation may be linked to modest improvements in blood sugar control and triglyceride levels in kidney transplant recipients, though the effect on fasting glucose alone was not statistically significant.

The HbA1c improvement (0.30% reduction between groups) is clinically modest—roughly equivalent to a modest lifestyle intervention—but occurred alongside a meaningful triglyceride drop of 24 mg/dL, which relates to cardiovascular risk in this high-risk population. Notably, fasting glucose did not significantly differ between groups on adjusted analysis, suggesting the benefit may be driven more by overall glycemic variability or postprandial glucose control rather than basal glucose. The mechanism likely involves melatonin's antioxidant and anti-inflammatory properties, which could improve insulin secretion and lipid metabolism in the transplant setting. This study adds to growing evidence that melatonin influences metabolic function beyond sleep, though effect sizes remain small. The 3-month duration is a significant limitation; it is unclear whether benefits persist, increase, or plateau over 12 months or longer. Notably, no adverse kidney function changes were observed, suggesting safety in this population. Subgroup analysis by immunosuppressive regimen or baseline glucose control was not reported, which would have been informative.

Takeaway · Cadence

If you are a kidney transplant recipient managing metabolic risk, melatonin supplementation at moderate doses may be worth discussing with your transplant team as a possible adjunct to diet and exercise—it suggests modest benefits without apparent harm to kidney function. Consider pairing it with consistent sleep timing and stress management, which also support metabolic health. This is early evidence, so ongoing monitoring of blood sugar and lipids would remain important rather than expecting melatonin alone to reverse these trends.

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References

Effect of Melatonin Supplementation on Glycemic and Lipid Profiles in Kidney Transplant Recipients: A Clinical Trial. — Iranian journal of kidney diseases (Read the original)

#melatonin #kidney-transplant #glycemic-control #triglycerides