Neuropathy in Prediabetics: Is Oxidative Stress to Contribute?

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

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).

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.

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