Effectiveness of additional therapy with vitamin D (5.000 IU) on reducing diabetic neuropathy pain

Background and objectives. Diabetic neuropathy is microvascular complication of diabetes mellitus that attacks the pe - ripheral nervous system and manifested as persistent electrocution pain. Patients with diabetic neuropathy are often found in conditions of vitamin D deficiency. Vitamin D has a neuroprotective effects that plays a role in increasing axono - genesis, preventing nerve degeneration, and is an anti-inflammatory agent that can reduce diabetic neuropathy pain. Determine the effectiveness of additional therapy with Vitamin D 5.000 IU on the reduction of diabetic neuropathy pain in patients with diabetes mellitus at Bethesda Hospital, Yogyakarta. Materials and methods. This study is a Randomized Controlled Trial that has been completed. Data were taken from pa - tients with diabetic neuropathy diagnosed by Diabetic Neuropathy Examination and Diabetic Neuropathy Symptoms at Bethesda Hospital, Yogyakarta. There were 34 subjects involved and divided into two groups: treatment group given symptomatic therapy with additional Vitamin D 5.000 IU and the control group receiving only symptomatical therapy. Furthermore, pain intensity development data using VAS at weeks 0, 4, and 8 were analyzed using non-parametric Mann Whitney test. Results. Both groups experienced a decrease in pain intensity, but the treatment group which was given symptomatic therapy with additional vitamin D 5.000 IU was significantly better as seen from the difference between the VAS rate be - fore and after therapy (p=0.010) (p<0.05). Conclusions


INTRoDUcTIoN
Diabetes mellitus is a condition of hyperglycaemia due to the body's inability to produce the insulin hormone or insulin resistance occurs [1].The International Diabetes Federation stated that in 2019, diabetes sufferers in the world reached 463 million people, while based on 2018 RISKESDAS data in Indonesia, the number of diabetes sufferers in Yogyakarta reached 15,540 people [1,2].
Diabetic neuropathy is a microvascular complication of diabetes mellitus that affects the peripheral nervous system with symptoms of continuous tingling, burning, prickling, or electric shock [3].This pain can be found in 30-50% of diabetes mellitus patients [4].
Hyperglycaemia is associated with increased polyol pathway activity, where the affinity of the aldose reductase enzyme to glucose is higher, resulting in the accumulation of sorbitol and increased activity of the sorbitol dehydrogenase enzyme.The accumulation of sorbitol in nerves that cannot pass through the cell membrane, can increase the intracellular osmotic pressure and cause osmotic stress, thereby interfering with axonal transport and damaging the nervous structure.Hyperglycaemia also causes proteins to undergo non-enzymatic glycation, transforming them into AGE (advanced glycation end-products) and binding to their receptor, RAGE, triggering oxidative stress, increased proinflammatory cytokines activity, and NF-κB expression, leading to nerve dysfunction and diabetic neuropathy [4,5].
Vitamin D is neuroprotective which plays a role in increasing axonogenesis and preventing nerve degeneration [6].Vitamin D also acts as an anti-inflammatory agent by inhibiting cytokine macrophage colony-stimulating factor (M-CSF), enzyme inducible nitric oxide synthase (iNOS), and decreasing NF-κB synthesis.Vitamin D deficiency conditions are associated with increased intensity of pain in diabetic neuropathy [7].Pain intensity measurement can be done using visual analogue scale (VAS), which is a measure of a straight line with a length of 10 cm where the left end indicates no pain and the right end indicate the worst pain [8].
The study aims to determine the effectiveness of supplemental therapy with 5000 IU of vitamin D in reducing the pain of diabetic neuropathy in patients with diabetes mellitus at Bethesda Hospital in Yogyakarta, Indonesia.

MATERIALS AND METHoDS
The study uses secondary data from the Randomized Controlled Trial research design that existed from February to April 2021.There are 34 subjects of diabetes mellitus patients with diabetic neuropathic pain at Bethesda Hospital, Yogyakarta.The sample count is calculated using openepi software with a sample of at least 14 people.The subjects were divided into 2 groups: the control group receiving only symptomatic therapy and the treatment group who received additional therapy of 5,000 IU of vitamin D. In this study, pain scale were assessed using the VAS before and after intervention in weeks 0, 4 and 8.
The criteria for inclusion in this study included (1) patient with type 2 diabetes mellitus with diabetic neuropathic pain who agreed to participate in the study, (2) patients who had been diagnosed with diabetic neuropathies based on Diabetic Neuropathy Examination (DNE) and Diabetic Neuropathy Symptoms (DNS), (3) patients who were over 18 years of age, while, the exclusion criteria include (1) patients who are allergic to vitamin D, (2) patients who had diseases or disorders in the liver and kidneys, (3) woman who were pregnant and lactating, (4) patients who stopped controlling in the middle of the course of the study, ( 5) patients who died before the end of the study.
Univariate analysis is done to find out the baseline characteristics of each subject.Bivariate analysis uses the chi-square test to determine the relationship between confounding variables and independent variables to dependent variable.The study also conducted a normality test to determine the distribution of data using the Shapiro-Wilk test and non-parametric Mann Whitney test using SPSS software to find out the relationship between intervention and decreased intensity of pain in diabetic neuropathy before and after therapy in both groups.
This research has been ethically validated by the Bethesda Hospital Yogyakarta research ethics commitee (No. 63/KEP-RSB/XII/21).

RESULTS AND DIScUSSIoN
The study was attended by 34 subjects, with 19 females (55.9%) over 15 males (44.1%).A cohort study by Abraham, A et al., (2018) stated that women suffer more from diabetic neuropathic pain with higher intensity of pain than men after measuring using VAS [9].Singh, A et al., (2016) stated that estrogen is neuroprotective so that a decrease in estrogen levels in postmenopausal women can increase the risk of diabetic neuropathy [10].In this study, the age ratio was 63.1471±9.03573years, where diabetic neuropathy was discovered as the age increased due to the reduction in the body's ability to suppress free radicals that caused endothelial damage and resulted in diabetes neuropathy [11].Long-term diabetes mellitus in both groups averaged 9.3382±7.58659years with both dominant controlled diabetes.Nisar et al., (2015) stated that long duration of diabetes accompanied by poor glucose control leads to metabolic disorders, endothelial injury, and an increase in oxidative prod-ucts and glycosylation end products [12].Both groups were also dominated by subjects with vitamin D deficiency (70.6% vs 58.8%).Sari et al. (2020) stated that diabetic neuropathy was often associated with vitamin D deficiency because it was found that serum vitamin D levels were lower compared to those who did not have diabetic neuropathy [6].Patients with diabetes who have hypertension are targeted to have blood pressure below 130/80 mmHg.Diabetes with hypertension can increase the risk of macrovascular and microvascular complications so antihypertensive drugs such as angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) are needed [13].According to the American Diabetes Association, patients with diabetes mellitus are given anti-platelet aspirin, especially to those with a history of atherosclerosis to reduce the risk of cardiovascular disease [14].Administration of statin is recommended in patients with diabetes mellitus  1].
In week 0 and week 4, both groups have a p value =1.000 and 0.277, which means there was no significant difference (mean VAS 5.82vs5.69and 3.39vs4.47).In week 8, both groups have a p value =0.033, meaning there is a significant differential (VAS ratio 1.97vs3.58).The difference between both groups at pre-therapy with week 8 was 3.8471vs2.1059(p = 0.010).The decrease in the scale of diabetic neuropathy pain in the treatment group was significantly better than in the control group [Figure 1].
Neither the treatment group nor the control group obtained subjects who experienced side effects of the drug (Table 2).
Vitamin D is a neurotrophic hormone that has neuroprotective effects by increasing axonogenesis and preventing nerve degeneration.Diabetic neuropathy is often associated with a decrease in nerve growth factor (NGF) in the nerves, whereas vitamin D can enhance the NGF synthesis that plays a role in neural development.Vitamin D also plays a role in inhibiting COX-2 by stimulating 15-prostaglandin dehydrogenase (15-PGDH).The 15-PGDH enzyme will degrade prostaglandins and inhibit prostaglandin-E2 receptors.When prostaglandins are not inhibited, it can mediate neuropathic pain in the bone marrow during PGE2 depolarizes.Vitamin D suppresses proinflammatory cytokines such as TNFα and M-CSF in astrocytes and microglia.Vitamin D also inhibits the iNOS enzyme that produces NO (a neurotransmitters in the nociceptive pathway that cause central sensitization) so that it can reduce pain and nerve damage.Vitamin D also reduces the function of neutrophils that produce cytokines and NO when tissue damage occurs because the more neutrophils, the worse the progression of diabetic neuropathy [13].
The limitation in this study is to use secondary data of completed RCT research so that researchers cannot know the research process.Besides, this study's observation time is limited to eight weeks.coNcLUSIoN Supplemental vitamin D therapy of 5,000 IU in patients with diabetes mellitus with diabetic neuropathic pain can decrease the intensity of pain more sharply compared to simply receiving symptomatic therapy without additional therapy.

FIGURE 1 .
FIGURE 1. Graphic rate shows a comparison of the pain intensity ratios between the two groups measured with VAS from before therapy (week 0), week 4 and week 8 after therapyTAbLE 2. Tables of side effects Side effects

TAbLE 1 .
Baseline characteristic of subjects