The level of peripheral myelin protein and vitamin D in blood serum among patients suffering diabetes mellitus type II and hearing impairment
Authors: Shidlovskaya Tetiana A. , Shidlovskaya Tamara V. , Navalkivska Nadiya Ya. 
Published: December 2021

Topicality: While diabetes mellitus is often observed hearing impairment, including sensorineural hearing loss (SNHL). On the other hand, metabolic changes, disorders of the hemostasis system, lack of vitamins and minerals can lead to the development of SNHL.
Aim: to examine the level of peripheral myelin protein (PMP) and vitamin D in patients with diabetes mellitus type II with hearing impairment.
Materials and methods: Were examined 43 patients with diabetes mellitus type II, who, according to subjective audiometry, revealed SNHL of the I-II degree according to the International Classification. We divided patients into two groups: group 1st
included 22 patients without complications, group 2nd – 21 patients with complications of diabetes mellitus and sudden changes in blood sugar levels in the anamnesis. As a comparison group were examined 15 patients with SNP without high blood sugar. The control group consisted of 15 healthy individuals.
Results and discussion: When analyzing the results of the study, it was found that in patients with diabetes mellitus and SNHL (groups 1st and 2nd) there was a significant increase of the level of PMP comparing with the control and the comparison group. Moreover, in group 2nd (with complicated diabetes mellitus) the increase of the level of PMP in the blood serum was reliably more significant than in group 1st. In patients with diabetes mellitus group 1st the level of PMP was from 2.3 to 9.8 ng/ml (average value of 7.2±0.5 ng/ml), in group 2 PMP had a level of 8.5 to 37.2 ng/ml (average value of 24.3±1.7 ng/ml). This is significantly (P<0.01) more than in the control group. Elevated levels of PMP in patients with diabetes mellitus may indicate the processes of demyelination, damage of neural structures, which are more pronounced in the complicated course of diabetes, which, obviously, have some significance in the development of SNHL in diabetes mellitus type II.
As for the content of vitamin D, certain reductions in its level were observed in all groups of examined patients with SNHL. However, in patients with SNHL without diabetes mellitus, this decrease was not differing significantly from the control values. But in both groups of patients with SNHL on the background of diabetes mellitus, this difference was significant, especially in group 2nd. Decreasing the level of vitamin D in blood serum, more expressed at the complicated course of diabetes mellitus in patients with SNHL testifies of a certain role of this vitamin in deepening of metabolic disturbances at such patients, and consequently – faster and more expressed development of complications.
While the analysis of the distribution of patients with deviation of PMP level and vitamin D, it was found that in groups of patients with diabetes, especially in group 2nd with a complicated course, in blood serum there was significantly more often than in the comparison group a lack of vitamin B and increasing of PMP. Moreover, in group 2nd deviations from the norm in the level of PMP were also significantly more often than in group 1st. In the group of SNHL without diabetes mellitus (group 3rd) vitamin D deficiency was observed only in 13.3% of cases. A deficiency of vitamin D in group 2nd occurred significantly more often not only comparing with the control and comparison group, but also relatively to group 1st, with a milder course of diabetes. Thus, in group 2nd in patients with diabetes and SNHL, the lack of vitamin D occurred in 26.6% and its deficiency – in 73.3% of cases.
In general, a decrease of vitamin D levels occurred in 100% of patients in group 2nd and in 80% in group 1st, while in group 3rd
– 30%.
Thus, researches have shown that in all studied groups of patients with SNHL on the background of diabetes mellitus type II there are deviations from the norm in the content of PMP and vitamin D in the blood serum. Moreover, the most pronounced disorders were found in the examined, who also had a complicated course of diabetes mellitus type II, the episodes of hypoglycemia in the anamnesis. This indicates the possible role of a complicated course of diabetes mellitus type II on the development of disorders (including demyelinating processes) in the neural structures of the auditory analyzer.
Conclusions: In patients with diabetes mellitus type II and sensorineural hearing loss there is a significant increase in the content of PMP in blood serum, more pronounced in complicated diabetes, which may indicate the processes of demyelination and damage of neural structures.
In patients with sensorineural hearing loss on the background of diabetes mellitus type II there is a significant (P <0.01) reduced levels of vitamin D compared with the control, the severity of reducing indicates its lack and even deficiency, especially occurred on the background of complications of diabetes mellitus.
Patients with diabetes mellitus type II with sensorineural hearing loss, who have a complicated course, polyneuropathy, episodes of a severe changes of sugar levels in anamnesis, there is a significant (P<0.05) more pronounced increasing levels of PMP and decreasing of vitamin D than in patients with milder course of disease.
The obtained data may indicate an important role of demyelinating processes and vitamin D deficiency in the development of sensorineural hearing impairment among patients with diabetes mellitus type 2.