Consumption of melatonin supplement improves cardiovascular disease risk factors and anthropometric indices in type 2 diabetes mellitus patients: a double-blind, randomized, placebo-controlled trial

Double-blind, randomized, placebo-controlled trial in adults with type 2 diabetes mellitus recruited from endocrinology/metabolism clinics in Iran. Eligible participants were 30 to 60 years old, had BMI 18.5 to 30 kg/m^2, and had diabetes for more than 5 years.

Adults with type 2 diabetes received melatonin tablets for 8 weeks: 2 tablets daily, with each tablet containing 3 mg melatonin, taken once daily 1 hour before bedtime. The active regimen therefore provided 6 mg melatonin per day; the comparator was placebo.

Melatonin improved several cardiovascular and anthropometric measures over 8 weeks, but not all cardiometabolic markers changed. In the melatonin group, systolic blood pressure fell from 124.00 ± 15.27 to 114.40 ± 12.60, mean arterial pressure from 90.66 ± 9.90 to 84.80 ± 8.33, and pulse pressure from 50.00 ± 11.54 to 44.40 ± 11.21. Measures of adiposity also improved, including weight (73.88 ± 8.85 to 70.28 ± 7.57), BMI (27.38 ± 2.16 to 26.11 ± 2.39), waist circumference (101.60 ± 10.07 to 99.48 ± 9.54), hip circumference (106.76 ± 10.04 to 103.04 ± 9.32), and BAI (32.95 ± 5.68 to 29.74 ± 4.56). AIP did not meaningfully change, and ABSI increased slightly; no adverse events were reported.

The intervention was short, lasting only 8 weeks, which limits conclusions about durability and long-term safety. The study was conducted in adults with type 2 diabetes from one region of Iran, reducing generalizability. Some outcomes did not improve, including the atherogenic index of plasma, and ABSI increased slightly despite overall anthropometric improvement.