Neuroendocrinology Letters, vol.42, no.1, pp.33-42, 2021 (SCI-Expanded)
BACKGROUND: Oxidative stress plays a crucial role in the pathogenesis of diabetic
peripheral neuropathy. Melatonin is one of the most powerful antioxidant
substances and its role in the pathogenesis of diabetes has been the focus of much
research. However, no data exist on melatonin levels in diabetic peripheral
neuropathy. We investigated how levels of urinary 6-sulfatoxymelatonin, the main
metabolite of melatonin, differed in diabetic peripheral neuropathy.
METHODS: A total of 127 participants were enrolled into 3 groups: diabetic
neuropathy (n=43), diabetes but no neuropathy (n=44), and controls (n=40).
Neuropathy was diagnosed using the Michigan Neuropathy Screening Instrument.
Melatonin level was evaluated by measuring 24-hour urine 6-sulfatoxymelatonin
RESULTS: We found significant differences in urinary 6-sulfatoxymelatonin
levels between the 3 groups (p=0.023). The distribution of 6-sulfatoxymelatonin
among all diabetic participants was significantly lower than in the control group
(p=0.006). However, there was no difference in diabetics with and without
neuropathy (p=0.792). 6-sulfatoxymelatonin levels were negatively and weakly
correlated with plasma glucose(r = −0.211, p=0.017) and positively and weakly
correlated with microalbuminuria (r= 0.209, p=0.023). Regression analysis was
found a significant relationship between age (B = 0.826, 95% Cl=0.227 to 1.426),
insulin use (B = 14.584, 95% CI= 3.857 to 25.311), glomerular filtration rate (B =
0.248, 95% CI= 0.018 to 0.478) and 6-sulfatoxymelatonin levels. 6-sulfatoxymelatonin levels in insulin users were significantly higher than they were in nonuser
CONCLUSION: Urinary 6-sulfatoxymelatonin levels were lower in diabetics but
the presence of neuropathy did not affect 6-sulfatoxymelatonin levels. Insulin may
improve melatonin levels in diabetics.