Neuropathy in Prediabetics: Is Oxidative Stress to Contribute?

Abstract

Objective: To assess the association of oxidative stress and serum vitamin D levels in sensory neuropathy in prediabetes.

Methods: Serum and urine levels of 8-OHdG (a marker of oxidative stress) and serum levels of vitamin D were compared in prediabetic patient having sensory neuropathy to those who did not have sensory neuropathy as determined by VPTs measured by Digital Biothesiometer and MNSI (Michigan Neuropathy Screening Instrument).

Result: A total of 60 prediabetic cases between 35 years to 60 years were included in this study. Among all the prediabetic subjects, 43.3 % subjects had neuropathy according to VPTs measured by Biothesiometer. T-test analysis suggested that serum levels of 8-OHdG were significantly higher in subjects with neuropathy than subjects without neuropathy (1006.58 ± 511.8 vs 688.6 ± 607.3, p value = 0.035). Urinary levels of 8-OHdG were also significantly higher in subjects with neuropathy than subjects without neuropathy (699.35 ± 419.5 vs 474.57 ± 402.5, p-value = 0.04). No such significant difference however was present in serum levels of vitamin D between neuropathic and non-neuropathic prediabetics (20.13 ± 18.44 vs 16.96 ± 11.72, p value = 0.419. VPTs were found to have statistically significant positive correlation with serum 8-OHdG {, Pearson Correlation Coefficient= 0.317(R), 0.307(L); p-value=0.014(R),0.017(L)} and urine 8-OHdG levels{Pearson Correlation Coefficient= 0.288(R), 0.255(L); p-value=0.026(R), 0.049(L),}. According to MNSI physical assessment score (> or = 2), 38.3 % subjects (23 subjects) had neuropathy. MNSI score is positively correlated with serum 8-OHdG (Pearson Correlation Coefficient = 0.308; p-value = 0.017). Correlation with urine 8-OHdG was not statistically significant (Pearson Correlation Coefficient= 0.687; p value = 0.06). Correlations of MNSI scores {Pearson Correlation Coefficient=0.14, p-value=0.287} and VPTs{Pearson Correlation Coefficient= 0.058(R), 0.189(L); p-value=0.660(R), 0.148(L)} with serum vitamin D levels were not statistically significant.

Conclusion: Oxidative stress, as confirmed by the biomarker, 8-OHdG, has a important role in the development of this sensory neuropathy.