Study Links Reduced Melatonin to DR

The research, which analysed 12 studies measuring melatonin concentrations across various body fluids, found strong evidence that patients with DR experience reduced nocturnal melatonin production compared to those without the condition.¹ 

While studies examining salivary melatonin levels showed no significant differences between type 2 diabetes patients with and without DR, research measuring serum melatonin levels produced inconsistent results across different stages of the disease.Most concerning was the finding that only 33% to 57% of DR patients had detectable dim light melatonin onset (DLMO) in saliva and serum respectively. DLMO serves as a highly accurate biomarker for circadian regulation, suggesting significant disruption to normal sleep-wake cycles in affected patients. 

The study adds to growing evidence of the complex interplay between metabolic disorders and circadian rhythm disruption in ocular complications. 

All studies evaluating overnight melatonin production through urinary aMT6s (6-sulfaoxymelatonin) levels demonstrated a clear association between DR and lower nocturnal melatonin production, providing the most consistent evidence across the research. The researchers concluded that while DR patients show evidence of reduced nocturnal melatonin production, there were no significant changes in melatonin circadian timing. These findings may inform future therapeutic approaches and shed light on the importance of circadian health in diabetes management. 

The study adds to growing evidence of the complex interplay between metabolic disorders and circadian rhythm disruption in ocular complications. 

Reference

1. Senthil MP, Devlin E, Chakraborty R, et al. The role of melatonin and circadian rhythms in the pathogenesis of diabetic retinopathy: A systematic review. Diabetes Metab Syndr. 2025 Feb;19(2):103202. doi: 10.1016/j.dsx.2025.103202.